In the Vedic religion, the word vajra originally referred to natural phenomena, that is, lightning or thunderbolts, and it was considered to be a weapon of the god Indra. Later, when it was incorporated into Buddhism, its destructive power took the concrete form of a pestle and was internalized as the “destruction of worldly desires.” In Abhidharma Buddhism, the destructive power of the vajra was likened to the power of samadhi and called the “concentration compared to a vajra” (vajropamasamadhi 金剛喩定), and was defincd as the concentration of an instant experienced immediately becfore before the ultimate stage of deliverance. In other words, this concentration destroys the worldly desires that need to be severed in the stage of intellectual practice (darsana-marga 見道) and spiritual practice (bhavana-marga 修道), and it is the final concentration on the path leading to deliverance. In the theory of practice in the Mahayana, this concentration is reconstructed as the practice of the bodhisattva (bodhisattvacarya). When one analyzes its development on the basis of the Prajñaparamita Sutras, in which it was systematized for the first time in the Mahayana, it becomes clear that its structure is such that when a bodhisattva confirmed as having reached the stage of bodhisattva (bodhisattva-nyama)enters into the vajromasamdhi, the “intelligence of a single instant” (eka [la] ksana-samayukta prajña-)arises in his concentration, followed by the “intelligence of all-knowing” (sarvakarajñata)through that intelligence.
