122
Śrīmad-Bhāgavatam
[Canto 6, Ch. 16]
tvānām —of all existences;  yat —which;  dhruvam —permanent;  tat —that;  eva —certainly;  antarāle —in the middle;  api —also.
TRANSLATION
You exist in the beginning, middle and end of everything, from the most minute particle of the cosmic manifestation—the atom—to the gigantic universes and total material energy. Nonetheless, You are eternal, having no beginning, end or middle. You are perceived to exist in these three phases, and thus You are permanent. When the cosmic manifestation does not exist, You exist as the original potency.
PURPORT
The  Brahma-saṁhitā  (5.33) says:
advaitam acyutam anādim ananta-rūpam ādyaṁ purāṇa-puruṣaṁ nava-yauvanaṁ ca vedeṣu durlabham adurlabham ātma-bhaktau govindam ādi-puruṣaṁ tr.m ahaṁ bhajāmi
“I worship the Supreme Personality of Godhead, Govinda [Kṛṣṇa], who is the original person—absolute, infallible, without beginning, although expanded into unlimited forms, still the same original, the oldest, and the person always appearing as a fresh youth. Such eternal, blissful, all-knowing forms of the Lord cannot be understood even by the best Vedic scholars, but they are always manifest to pure, unalloyed devotees.” The Supreme Personality of Godhead has no cause, for He is the cause of everything. The Lord is beyond the workings of cause and effect. He is eternally existing. In another verse the  Brahma-saṁhitā  says,  aṇḍān-tara-stha-paramāṇu-cayāntara-stham : the Lord exists within the gigantic universe and within the atom. The descent of the Lord into the atom and the universe indicates that without His presence, nothing could factually exist. Scientists say that water is a combination of hydrogen and oxygen, but when they see a vast ocean they are puzzled about where such a quantity of hydrogen and oxygen could have come from. They think that everything evolved from chemicals, but where did the chemicals come from? That they do not know. Since the Supreme Personality