大毘盧遮那成佛經疏 3.17

3.17

The sūtra says: “Furthermore, Lord of Mysteries! Just as when heaven sends down rain, bubbles are born, the various transformations of mantra-siddhi should be known to be also like this.” The Śrāvaka sūtras compare sensation to a floating bubble, while in the Prajñā[pāramitā sūtras] bubbles are used as a simile: although they have no real intrinsic nature, the causes and conditions are still real phenomena; among the ten similes, there is 'like an illusion/transformation', but the bubble simile is not clarified. Now the meaning of this sūtra's simile is again distinct: like rainwater in the summer, from within the rainwater various floating bubbles are born according to whether the drops are large or small, their shapes and types being diverse, yet the nature of water has one flavor and serves as its own cause and condition. Inquiring through the four propositions, there is no distinct phenomenon produced; therefore this bubble entirely accords with conditions. The arising of the bubble is the arising of water; the ceasing of the bubble is the ceasing of water; therefore this simile is used for the transformations of the mind itself. For instance, the practitioner, taking their own mind itself as the Buddha, is in turn shown the upāya of awakening by the mind-Buddha, entering progressively into immeasurable Dharma gateways. Furthermore, taking the mind as the maṇḍala, this object serves as a condition for the mind, able to produce manifold inconceivable transformations. Therefore, the practitioner contemplates with the simile of a floating bubble, knowing it is not separate from their own mind, and thus does not give rise to attachment. The Expository Treatise also says: “Those who cultivate concentration possess fourteen transformations; devas, nāgas, ghosts, and spirits can also perform transformations. Like magically created light having no fixed substance, it exists simply when the mind gives rise to it, and ceases when the mind ceases; this phenomenon has no beginning, middle, or end; its arising comes from nowhere, and its cessation goes nowhere; one should know that all phenomena are also like this. Furthermore, just as the mark of transformation is pure like empty space without defilement and not stained by sin or merit, all phenomena are also like this: the nature of phenomena, suchness, and the reality-limit are spontaneously and ever pure. For example, the four great rivers of Jambudvīpa each have five hundred minor rivers as their retinue; these waters have manifold impurities, but entering the great ocean, they all become pure.” This shares the same meaning as the bubble simile.