大毘盧遮那成佛經疏 3.38

3.38

「住勇健菩提心」者，勇健是雄猛無怯弱義。所以須此心者，以真言行者未見真諦以來，當有違順境界，或現種種可畏形色、或作異聲乃至震動大地，或有大力毘那野迦現作留難。爾時安心不動、無有退屈，依於法教而淨除之。猶行者見此淨菩提心有大義利故，自然出生入死無怖畏想，彼彼魔事不能留礙也。又未見菩提心時，於瑜伽中當有種種相見，所謂地水火風虛空、青黃赤白黑色等諸異相貌。爾時心未明了故不能甄辨，亦不應生退轉之意。但作是念：「此事非無因緣。若我見諦時，於菩提心明了無礙，自當解耳。」又當以十緣生句觀之，心不取捨，但當勇進行菩薩道。既證菩提心已，即知往昔某時有如是相，復於某時更有如是事相，皆為如是因緣，無不鑒其先兆、識其本末也。復次行者照見心明道時，即於無盡大願得堅固力，乃至毘盧遮那金翅鳥王俯觀法界大海如視明鏡，奮止觀翅搏天人龍，乃是勇健菩提心也。

"Abiding in the valiant bodhicitta": valiant means heroic, bold, and free from timidity. The reason one must have this mind is that before a mantra practitioner has seen the true reality, there will be conditions that go against or follow along [with his inclinations]. Either terrifying forms and colours may appear, or strange sounds may be made, even shaking the great earth, or mighty Vināyakas may appear to cause obstacles. At that time, [the practitioner] keeps his mind pacified and unmoving, without retreat or bowing down, and purifies and removes them relying on the Dharma teaching. Just as a practitioner, seeing that this pure bodhicitta has great benefit, naturally goes forth through life and death without fearful thoughts, so those various demonic affairs cannot obstruct or hinder him. Furthermore, before one has seen the bodhicitta, in yoga various marks will be seen, namely different signs such as earth, water, fire, wind, space, and blue, yellow, red, white, and black. At that time, because the mind is not yet clear, one cannot discern them, yet one should not give rise to any thought of falling back. One should merely think: "This matter is not without cause and conditions. When I see the truth and am clear and unhindered regarding the bodhicitta, I will naturally understand it." Moreover, one should contemplate them with the ten clauses of conditioned arising, neither accepting nor rejecting with one's mind, and simply advance valiantly on the bodhisattva path. Once one has realized the bodhicitta, one will immediately know that at a certain time in the past there was such a sign, and again at a certain time there was such a matter, all due to such causes and conditions; there will be none whose portents one does not perceive or whose origins and ends one does not recognize. Furthermore, when the practitioner clearly perceives the path of mental clarity, he attains firm strength in the inexhaustible great vows, up to the point where, like the king of golden-winged birds (Garuḍa) [who is] Vairocana looking down at the great ocean of the dharmadhātu as though gazing into a clear mirror, he flaps the wings of śamatha and vipaśyanā to strike gods, humans, and nāgas; this is the valiant bodhicitta.