The reflected moon as analogy for the way things exist has frequent sources in Sūtra. In “The Prophecy of the Magician Bhadra’s Attainment of Buddhahood” the Venerable Ānanda praises the Buddha:
You understand the profound doctrine of emptiness
So that you hold no view of self,
A personal identity, or a sentient being.
You abandon the extreme views
Of existence and nonexistence.
You know well that past, present, and future
Are like the moon mirrored in water.
However, the blog title Moon in Rippling Water was directly inspired by the opening verses of Candrakīrti’s Supplement to the Middle Way (Madhyamakāvatāra):
Homage to that compassion for migrators who are
Powerless like a bucket traveling in a well
Through initially adhering to a self, an ‘I,’
And then generating attachment for things, ‘This is mine.’
[Homage to that compassion for] migrators
Seen as evanescent and empty of inherent
Existence like a moon in rippling water.
Candrakīrti first pays homage to great compassion observing (i.e. taking as its focal object) migrators wandering powerlessly in states of suffering existence, like a bucket traveling in a well. Tsongkhapa glosses,
By what agency do sentient beings enter into cyclic existence? By just this extremely unpeaceful, untamed mind. Where and how do they wander? From the Peak of Cyclic Existence to the Most Torturous Hell without the slightest interruption in their circling. By what causes and conditions do they wander? By the power of contaminated actions and afflictions. They wander in the bad migrations by the power of nonmeritorious actions and afflictions, and in happy migrations by the power of meritorious and unmoving actions and their afflictions. To be born in bad migrations the process operates automatically and without effort, but it is difficult to be born in happy migrations because great effort must be made to achieve their causes.
To generate an unbearable ( as opposed to ordinary worldly) compassion on behalf of others, understanding of the evolution of how sentient beings come to suffer in cyclic existence is crucial and must be personally applied. As Tsongkhapa explains, “If your mind has not been affected by thinking about the way that you yourself wander in cyclic existence, then when you think about these modes of suffering in other sentient beings, there is no way that you as a beginner can find their suffering unbearable.”
If “beings are tormented more than once by the three sufferings” because the process is “uninterrupted, and every day—like ripples in water,” then how can we let our compassion be sporadic or shallow? Or partial? Might we only generate compassion when our friend suffers? Or obviously suffers? Or remain indifferent toward someone who is seen to suffer yet leaves us fundamentally unmoved because they have “neither helped nor harmed one”? “It is an important essential,” Tsongkhapa insists, that “one must generate a sense of strong cherishing and affection for sentient beings” otherwise we will be no better than “prattling parrots” mouthing compassion.
Secondly, with the words “compassion for migrators seen as evanescent,” Candrakīrti pays homage to compassion “observing phenomena.” This involves seeing how suffering sentient beings (encumbered as they are with afflicted aggregates) are qualified by momentary disintegration “like a moon in water stirred by a breeze.”
It also understands how they are empty of being permanent, partless and independent as well as self-sufficient and substantially existent persons. Because bodhisattvas fearlessly see reality as it is (de zhin nyid, tathatā, thatātva, tattva), they correctly and fully comprehend how the ignorance compelling sentient beings to constantly undergo sufferings is both reversible (like applying an antidote to poison) and unnecessary (because adventitious by nature). To be ignorant of being ignorant harbors an acute pathos.
Thirdly, homage is made to compassion “observing the unapprehendable.” This refers to sentient beings qualified as “empty of inherent existence like a moon in rippling water.” Tsongkhapa develops the analogy:
An image of the moon appears in a portion of very clear water that is covered by ripples from a mild breeze. The water that serves as the basic object is [actually] apprehended prior to the reflection, but the reflection is manifestly apprehended as a real moon that disappears each day. The excellent ones, namely, beings who are skilled in these ways, see momentary impermanence and the emptiness of the nature of the moon as it appears to be.
Due to being excellently “skilled in these ways,” Tsongkhapa concludes, bodhisattvas who have “come under the influence of compassion also see sentient beings in an ocean—the view of the transitory—which is filled by a vast blue river of ignorance,” the surface of which is “stirred by the winds of improper thought.” By seeing sentient beings “with the suffering of composition—momentary disintegration—descending on them” and recognizing that they are also “empty of inherent existence” bodhisattvas “generate great compassion” which, in turn, arises “from reflecting on the pleasantness of sentient beings and on the ways in which they wander in cyclic existence.”
The essential point is that sentient beings will suffer for as long as they fail to uproot their own “grasping at signs [of inherent existence].” In order to comprehend their plight and to actively assist them, Bodhisattvas must likewise comprehend the “ways in which they wander.”
This involves recognizing the most subtle innate form of ignorance—grasping at persons and phenomena as inherently, or truly, existent—together with methods capable of experientially generating its antidote. As Lama Zopa Rinpoche succinctly puts it, “This is the ignorance of unknowing that we must eradicate. This is the root of all the delusions, karma and the oceans of each realm’s sufferings. This is the source of all our unimaginable problems….It is nothing other than a wrong concept, one which, once investigated, makes no sense.” “Actually, when we analyze” Lama Zopa Rinpoche continues, “we discover this wrong concept which is the root of saṃsāra is really very funny. Very funny. Very Strange. If we investigate, there is actually no root of saṃsāra! No root of saṃsāra really!”
To understand (one can hardly say ‘enjoy’) this paradox requires huge and yet refined effort. Actually, it can be said that development of the extraordinary great compassion (which Candrakīrti describes in his Auto-Commentary as “the initial marvelous cause of Buddhahood”)  and the altruistic mind of enlightenment requires the greatest use imaginable of our current human intelligence precisely because the extraordinary development of compassion is predicated on overthrowing the ignorance of unknowing. In this way, great compassion is yoked to realisation of emptiness (suchness) in order to be developed to its fullest extent i.e. enlightened compassion. This is why Tsongkhapa writes: “When [practitioners] generate such compassions [referring to the three described in Candrakīrti’s verses] they generate an altruistic mind of enlightenment, thinking, ‘For the sake of sentient beings I will definitely attain the state of a Buddha.’”
Candrakīrti, in the verse preceding the two quoted above, clearly identifies “non-dual understanding” as one of three essential causes for becoming a “child of the Conquerors.” Wisdom realising emptiness, in other words, is essential prerequisite for one’s own evolution, one’s own growth into that most precious of entities: a baby Bodhisattva, as tender and yet resilient as a germinal sprout:
Hearers and middling realizers of suchness
Are born from the Kings of Subduers.
Buddhas are born from Bodhisattvas.
The mind of compassion, non-dual understanding,
And the altruistic mind of enlightenment
Are the causes of Children of Conquerors.
I would like to think (not with conceit but with awe) that the blog’s title shimmers and ripples with this significance, so great is the pure inspiration of its source.
 Sūtra 21, Taishō shinshū daizōkyō 310, pp. 486-492; translated into Chinese by Bodhiruci. Translated into English in C.C. Chang (editor), A Treasury of Mahayana Sūtras (The Pennsylvania State University Press: University Park and London, 1983), 19.
 Jeffrey Hopkins, Compassion in Tibetan Buddhism (Ithaca: Snow Lion, 1985), 116 & 120.
 Ibid., 118.
 Ibid.The three sufferings are: the suffering of change; the suffering of pain; the suffering of conditionality. To illustrate the first: “Pleasant feelings experienced by being in cyclic existence are like the pleasure felt when cool water is applied to an inflamed boil or carbuncle: as the temporary feeling faces, the pain reasserts itself. This is called the suffering of change and includes not only the feeling itself, but also the main mind and other mental processes that are similar to it, as well as the contained objects which, when perceived, give rise to that feeling.” Tsongkhapa, The Great Treatise on the Stages of the Path to Enlightenment (Lamrim Chenmo). Volume 1. Editor in Chief, Joshua W. C. Cutler (New York: Ithaca: Snow Lion Publications, 2000, 2002, 2004), 289. The second: “When a painfully inflamed boil makes contact with an irritant such as salt water; it is agonising. This is how you recognise the feeling of pain. Painful feelings like this constitute the suffering of pain, because as soon as they arise the body and the mind are tormented, as in the case of kidney pain.” Ibid., 290. The third: “Contaminated neutral feelings are like an inflamed boil which is in contact with neither soothing more irritating substances. Because those feelings coexist with dysfunctional tendencies, they constitute the suffering of conditionality, which, as explained above, does not refer to the feelings alone. Insofar as the suffering of conditionality is affected by previous karma, as well as the afflictions, and coexists with seeds that will produce future suffering and affliction, it coexists with persistent dysfunctional tendencies…In the same way that someone bearing a heavy burden cannot be happy so long as the burden must be borne, you too will suffer as long as you carry the burden of the appropriated aggregates.” Ibid, 290.
The suffering of conditionality is poignantly encapsulated in the foll0wing verse by Āryadeva (from his Four Hundred Stanzas):
Pleasure, when it increases,
Is seen to change into pain;
Pain, when it increases,
Does not likewise change into pleasure.
Ibid., 292. The reason: the conditions are present for the suffering of conditionality. For as long as the dysfunctional tendencies have not been remedied, we lean, or incline, or even veer towards suffering without further effort being required, as it were. Because it is pervasive (at least so long as the afflicted conditions are there) we might mistake this most subtle of the three sufferings to be natural. A mere fact of life. Even spontaneous. In reality it is no less adventitious than the other two and thus equally prone to eradication or cessation upon dis-assemblage of its constitutive conditions.
 Compassion in Tibetan Buddhism, 119.
 Ibid., 120.
 Writes Tsongkhapa, “When one determines that beings disintegrate momentarily, the existence of a permanent, partless, and independent person is eliminated in one’s mind. Thereby, one can ascertain the non-existence of sentient beings who are different entities from their mental and physical aggregates. At that time one understands that they are designated to the mere collection of the mental and physical aggregates. Sentient beings who are designated to the mere phenomena of the aggregates and so forth serve as the objects of observation, and thus this is called ‘compassion observing phenomena’” (ibid., 121).
Guy Newland paraphrases: “When one determines that sentient beings disintegrate moment by moment, one simultaneously realises simplicity that they are empty of being permanent, unitary, and independence upon having thus refuted the existence of a permanent, unitary, and independent person, one ascertains that sentient beings lack substantial existence–that is, that they are not self-sufficient entities that are different from their mental and physical aggregates but are merely designated in dependence upon the collection of impermanent aggregates…When a mind of great compassion is explicitly affected either by an earlier realisation of sentient beings as empty of being permanent, unitary, and independent or by an earlier realization of sentient beings as lacking substantial existence, the sentient beings whom that mind of compassion wishes to free from suffering appear to it as flickering or “rippling” with momentary impermanence, like the reflection of a moon in water stirred by a slight breeze.” Newland, Compassion: A Tibetan Analysis: A Buddhist Monastic Textbook (Boston: Wisdom Publications, 1984), 57-8.
 Compassion in Tibetan Buddhism, 120. Tsongkhapa points out that “Compassion observing the unapprehendable also does not observe sentient beings. It observes a special object: sentient beings who are empty of inherent existence.” Compassion: A Tibetan Analysis, 59. This means it shares a common locus with the second compassion but not necessarily the first: mere sentient beings. Ibid., 59-60. They are “mere” in the sense of not being qualified in any way.
Newland details how the moon analogy works in this context: “Just as a reflection of the moon in water appears to be the moon but is not, conventional phenomena such as sentient beings appear to exist inherently, but do not. Just as an ordinary intelligent person does not consider a reflection of the moon to be the moon, one who realizes subtle selflessness–the emptiness of inherent existence–does not assent to the deceptive appearance of phenomena as inherently, naturally, or truly existing. The self is not one of the aggregates that serve as its base of designation, is not the composite of those aggregates, and does not exist apart from those aggregates. Nevertheless, it does have mere nominal existence as an imputation by thought and within that context is able to perform functions such as taking rebirth. Great compassion that is explicitly affected by a previous realisation of emptiness of inherent existence observes sentient beings qualified with truthlessness and has the aspect of wishing that they be free from suffering. This third type of compassion is called “compassion observing the unapprehendable.” “Apprehendable” is an abbreviation for “apprehendable as truly existent,” which means “truly existent”; “unapprehendable” thus means “not truly existent.” Jay-dzun-ba explains that “compassion observing the unapprehendable” is a shortened form of “compassion observing sentient beings who lack true existence.” Ibid, 58.
Readers of the last post will recognize that this is another way of pointing out the combatibility of emptiness and dependent arising i.e. the illusory status of merely imputed–and therefore empty–things, namely, suffering persons entirely lacking existence from their own side and so amenable to radical transformation beyond suffering via exact targeting and elimination of its causes. Hence the responsive role of great compassion which is geared towards all beings who are considered alike in being equally qualified to obtain Enlightenment given the pre-requisite supportive circumstances.
 Compassion in Tibetan Buddhism, 120.
 Ibid., 120–21.
 Ibid., 122.
 Guy Newland, Compassion: A Tibetan Analysis: A Buddhist Monastic Textbook (Boston: Wisdom Publications, 1984), 19.
 Compassion in Tibetan Buddhism, 123. An astute reader will wonder whether this requires that all three must be generated prior to becoming a Bodhisattva. The answer is they must:”Jay-dzun-ba explains that Nāgārjuna and Chandrakīrti are indicating that a mind of compassion, non-dual awareness, and a mind of enlightenment are prerequisites for becoming a novice Bodhisattva. Thus, all three of these minds must be generated before one can become a Bodhisattva.
According to Jay-dzun-ba “the mind of compassion” (snying rje’i sems) in this context refers to great compassion. Great compassion observes all sentient beings and has the aspect of wishing that they be free from suffering. In order to generate such compassion it is necessary both to feel a sense of closeness or intimacy with all sentient beings and to be aware of their suffering.” Newland, ibid., 35-6. One also recognises that the only way one to perfectly free beings from suffering is to obtain enlightened omniscience on their behalf. This is why His Holiness the Dalai Lama describes compassion, along with emptiness, as keys to the highest state. And, in order to carry oneself there, one must enter the Bodhisattva vehicle.
But there is an obvious sequential complication if we interpret that “non-dual awareness” in this context refers to the mind attained upon the first moment of direct (rather than inferential) realisation of emptiness as only Ārya beings (i.e. those of the Path of Seeing and beyond and thus already thoroughly installed and progressed on the Bodhisattva path) have such realisation involving the mind realising emptiness and the object realised emptiness itself being inseparably fused like water poured into water. However, this consequence can be escaped if “the word “dual” in “non-dual awareness” is taken as not referring here to subject/object duality” but rather, “to the two extreme views, permanence and annihilation.” Ibid., 42.
As Newland elaborates: “The extreme of permanence in this context refers to the conception that reifies phenomena, superimposing upon them a natural or inherent existence that they do not possess. The extreme of annihilation is the view that phenomena do not exist at all, like the horns of a rabbit. A wisdom consciousness realizing emptiness discerns the final nature of phenomena–without superimposing inherent existence or denying mere conventional existence. Thus, since such a wisdom consciousness realizing emptiness is a view free of the two extremes, it is called a “non-dual awareness.” Ibid., 42
The conclusion: “The non-dual awareness referred to here must be a conceptual, inferential realisation of emptiness since it is a cause of a novice Bodhisattva and emptiness is not realized directly until the path of seeing.” Ibid.
 Ibid., 102.