大毘盧遮那成佛經疏 20.19

20.19

爾時執金剛祕密主白佛言：「世尊！願說諸尊，令威驗現前、令尊現形。諸真言修菩薩行諸菩薩，由作其形，令行者觀緣尊形，即本尊形同於自身，無有疑惑而得悉地。」如是說已。佛告執金剛祕密主言：善哉善哉祕密主！汝能問吾等。爾時金剛手祕密主白佛言：世尊！願說本尊靈驗，令諸真言行菩薩修行菩薩行，本尊形像觀。佛言：祕密主！諸尊有三種形，謂字、印、形貌也。彼字有二種，謂聲及菩提心。次印亦二種，謂有相、無相。相是色義，謂有像無像也。尊形亦二種，謂淨、非清淨。彼證淨形，形謂身也，體同空，離一切相。非淨，有相之身，即有顯形眾色。彼二種尊形，成二種事，有相故成有相，非相故隨生非相悉地。上亦列著之。次引佛為證，有相故成有相，佛常如是說也。若心住非想，即成非想也。佛語先標之也。是故成一切種，當住於悲想。言事隨心故，宜求出世也。既觀本尊形已，為無疑悉地得。此以上金剛手問也。本尊者，梵音娑也地提嚩多，若但云提嚩多者，直所尊之義也。尊亦云自尊，謂自所持之尊也。然彼行者，猶身印、真言及觀本尊此三事和合故，本尊即自降臨道場而來加被也。然此行者初行之時，尚是凡夫自無德力，何能即感佛菩薩等如是而應耶？但由彼佛菩薩等先立誠言大誓願故。若有眾生依我此法而修行之不虧法則者，我必冥應，或雖不來而遙加護之。若行人法則如法而不應赴，即是違本所願，故不得不應也。如方諸向月而水降，圓鏡向日而火生，因緣相應而無思念，此法亦可為喻。非是諸佛有心行而同凡夫之赴應也。若心不相應、事緣有闕，則本尊不加護念，故無應驗，非佛菩薩等之過也。然行者以此事故，當須正觀本尊清淨身。清淨身若見已，即以自身而為本尊身。如是無疑慮者，所求悉地無不成果也。經云緣者，即是行者若約其本尊作如是觀也。無疑者，猶與彼尊相應故，無復疑難之心也，是故所修必成。已上問竟。

At that time, the Secret Lord Vajrapāṇi addressed the Buddha, saying: "Bhagavat! We pray that you explain the deities, so that their majestic efficacy may manifest before us and the deities may manifest their forms. May the bodhisattvas of mantra who practice the bodhisattva deeds, by producing their forms and contemplating the forms of the deities, perceive the deity's form as identical with their own bodies, and attain siddhi without doubt." Having spoken thus, the Buddha told the Secret Lord Vajrapāṇi: "Excellent, excellent, Secret Lord! You are able to question us."
At that time, the Secret Lord Vajrapāṇi addressed the Buddha, saying: "Bhagavat! We pray that you explain the wondrous efficacy of the deities, so that all bodhisattvas of mantra practice, when cultivating the bodhisattva deeds, may visualize the bodily forms of the deities."
The Buddha said: "Secret Lord! Deities have three kinds of forms: syllables, mudrās, and bodily appearances. Those syllables are of two kinds: sounds and bodhicitta. Next, mudrās are also of two kinds: with marks and without marks. 'Mark' means visible form—that is, with imagery and without imagery. The deities' forms are also of two kinds: pure and non-pure. Those forms realized as pure—'form' meaning body—are identical in essence to space, free from all marks. The non-pure are bodies with marks, having visible shapes and various colors. Those two kinds of deities' forms accomplish two kinds of matters: because there are marks, they accomplish what has marks; because there are non-marks, they accordingly give rise to formless siddhi." The above has also been laid out.
Next, the Buddha is cited as proof: because there are marks, they accomplish what has marks, as the Buddha constantly taught. If the mind abides in the non-conceptual, it accomplishes the non-conceptual; this was first stated in the Buddha's words. Therefore, to accomplish all aspects, one should abide in compassionate contemplation. Because matters follow the mind, one ought to seek the transmundane. Having contemplated the deity's form, one attains siddhi free of doubt. The above is Vajrapāṇi's question.
"Deity" (iṣṭadevatā) is in Sanskrit *svādhidevatā*; if one simply says *devatā*, it means solely "revered one." "Deity" is also called "one's own deity," referring to the deity one upholds oneself. Through the harmonious union of these three matters—the practitioner's body mudrā, mantra, and visualization of the deity—the deity naturally descends to the maṇḍala site and bestows adhiṣṭhāna. However, when this practitioner first begins practice, being still an ordinary being without personal virtue or power, how could he immediately evoke the Buddhas, bodhisattvas, and others to respond like this? It is simply because those Buddhas, bodhisattvas, and others previously made truthful vows and great resolutions: "If any sentient being cultivates according to this Dharma of mine without failing the ritual rules, I will surely respond unseen, or even if I do not come, I will protect them from afar." If the practitioner's ritual procedure is done in accordance with the Dharma and they were not to respond, that would contradict their original vows; thus they cannot fail to respond. Just as the square pearl facing the moon causes water to descend, and the round mirror facing the sun causes fire to arise, causes and conditions harmonize without deliberate thought; this principle can serve as an analogy. It is not that the Buddhas have intentional thoughts and respond like ordinary beings.
If the mind does not correspond or the ritual conditions are lacking, then the deity does not grant protective care, and so there is no efficacious response; this is not the fault of the Buddhas, bodhisattvas, and the rest. Therefore, the practitioner must properly visualize the pure body of the deity. Having seen the pure body, one regards one's own body as the body of the deity. For one who is without doubt or hesitation in this way, there is no sought-after siddhi that does not bear fruit.
When the sūtra says "contemplate," it means that the practitioner engages in such visualization with regard to the deity. "Without doubt" means that because one corresponds with that deity, there is no longer any doubtful or hesitant mind; therefore, what is cultivated is definitely accomplished. The above finishes the question.