गोविन्द भाष्य (श्रील बलदेव विद्याभूषण - अचिन्त्यभेदाभेद वेदान्त ब्रह्मसूत्र भाष्य सटीक)

Purport by Śrīla Baladeva Vidyābhūṣaṇa Because it makes the entire universe tremble, this vajra must be the Supreme Personality of Godhead. This is so also because of the following statement of Brahma-vaivarta Purāṇa: cakraṁ caṅkramaṇād eṣa vajanād vajram ucyate khaṇḍanāt khaḍga evaiṣa heti-nāmā hariḥ svayam "Because He goes (caṅkramaṇa) everywhere He is called "Cakra" (moving in a circle). Because He moves about (vajana He is called "Vajra" (thunderbold). Because He cuts apart (khaṇḍana) the demons He is called "Khaḍga" (sword). These are names of Lord Hari." Also, because the word prāṇa (breath) and the word bhaya (fear) are used, the passage must refer to the Supreme Personality of Godhead. In these ways it is established that the word vajra here refers to the Supreme Personality of Godhead. Sūtra 40 jyotir-darśanāt jyotiḥ-effulgence; darśanāt-because of seeing. It is so because the vajra is described as jyotiḥ (splendor). Purport by Śrīla Baladeva Vidyābhūṣaṇa Before the passage discussed is the following statement (Kaṭha Upaniṣad 2.2.15): na tatra sūryo bhāti na candra-tārake (When He does not shine, then neither sun, moon, nor stars show their splendor). After the passage discussed is the statement (Kaṭha Upaniṣad 2.3.3) bhayād asyāgnis tapati (Out of fear of Him fire glows). In both these passages the Supreme Personality of Godhead is described as transcendental splendor, and therefore the passage describing the vajra (thunderbolt) between these two passages, must refer to the efulgent Supreme Personality of Godhead.