Bhagavad Gita Chapter 10, Verse 20

अहमात्मा गुडाकेश सर्वभूताशयस्थितः | अहमादिश्च मध्यं च भूतानामन्त एव च ||

aham ātmā guḍākeśa sarva-bhūtāśaya-sthitaḥ aham ādiś ca madhyaṁ ca bhūtānām anta eva ca

I am the Self, O Arjuna, seated in the hearts of all creatures. I am the beginning, the middle, and the end of all beings.

Krishna begins His enumeration by revealing His most fundamental manifestation: 'Aham ātmā'—I am the Self. 'Sarva-bhūtāśaya-sthitaḥ'—seated in the hearts of all beings. Krishna is the Self (ātmā) that dwells within every creature. This is the foundation: before listing specific manifestations, Krishna reveals that He is the Self in all beings. 'Aham ādiś ca madhyaṁ ca bhūtānām anta eva ca'—I am the beginning, the middle, and the end of all beings. Krishna is not just present in beings—He is their beginning (ādi), middle (madhya), and end (anta). This shows His complete presence: He is the source from which beings arise, the presence that sustains them, and the end toward which they return. This is the most fundamental manifestation: the Self in everything.