So what is that symptom? Symptom is that eternal, and temporary. So avatāra, incarnation, comes to glorify the eternal existence of the Supreme Lord. So any avatāra, any incarnation, he comes to glorify that "There is spiritual kingdom, there is God, and I have come to reclaim you to back to Godhead, back to home." This is the symptom.
So therefore, by that symptom we accept Lord Jesus Christ as śaktyāveśa avatāra, or Hazrat Muhammad, he's also. Because these two religious leaders of the world, they preached about the glorification of the Supreme Lord, and they sacrificed everything for preaching the glories of the Lord. Therefore . . . and their influence and their followers, there are . . . these are the symptoms by which we can understand that Jesus Christ and Hazrat Muhammad was . . . were śaktyāveśa avatāras.
So far Buddha is concerned, he's also considered śaktyāveśa avatāra. He preached this nirvāṇa philosophy. Although he did not speak about God—because it is considered that he was himself God—but the people amongst whom he preached, they were mostly atheistic people; therefore he did not preach about God. But he did not deny also. He simply wanted to make extinction of this present worldly activities. That was . . . yes. Nirvāṇa. And he represented the sacrificial renouncement.
He . . . you may remember that the Supreme Personality of Godhead, out of His six opulences, one opulence is renouncement. So Lord Buddha's life is renouncement. He was prince. He, he was in a very young time. He renounced the world and underwent severe penances. These are the symptoms by which we can understand that he's also śaktyāveśa avatāra. And the Bhagavad-gītā you'll find, yad yad vibhūtimat sattvaṁ mama tejo-'ṁśa-sambhavam (BG 10.41).
Anyone, not only Lord Buddha or other, but anyone, Lord, in the Bhagavad-gītā it is stated, anyone who has got some extraordinary power, uncommon power, he's to be considered vibhūti. Śaktyāveśa avatāra, there are two kinds: one directly empowered for particular mission, comes from the transcendental spiritual sky, and others, those who are in this material world, but they have got some specific power, uncommon power, not found in ordinary man. They are called vibhūti. This vibhūti (is) explained in the Bhagavad-gītā: yad yad vibhūtimat sattvaṁ mama tejo-'ṁśa sambhavam. That is out of the opulence of the Supreme Personality of Godhead.
- sanakādye 'jñāna'-śakti, nārade śakti 'bhakti
- brahmāya 'sṛṣṭi'-śakti, anante 'bhū-dhāraṇa'-śakti
Now, so far the principal śaktyāveśa avatāras are concerned, as mentioned by Lord Caitanya, now, what are the manifestation of opulences in each of these śaktyāveśa avatāras? He says that sanakādye, the Kumāras, the four Kumāras—Sanaka, Sanātana, Sananda, Sanat-kumāra—these four Kumāras, they were vastly learned, and they . . . first they preached the philosophical way of understanding the Absolute Truth. Sanakādye. Later on, they become devoted, devotees, and they have got a sampradāya, or party, they are called Nimbārka-sampradāya.