Those who know what is Absolute Truth, they say that is the Absolute Truth which is advaya-jñāna. Advaya-jñāna means without any duality. Just like here in this material world it is called dual world, duality. Everything cannot be understood absolutely. If I say . . . it is a, rather in ordinary language, relative world. Here everything is relative. Just like if I say: "father," "father" has no meaning if there is no son. Duality. If I say: "good," so unless I have got idea of bad, I cannot understand good. If I say "light," unless I have got conception of darkness, I cannot understand light.
So here everything is duality, relative knowledge, relative world, but in the absolute world everything is one, spirit. Here . . . because here we have got experience two energies, spiritual energy and material energy, working. The material energies are the physical elements, bhūmir āpo 'nalo vāyuḥ (BG 7.4): earth, water, fire, air, sky and, in subtle form, mind, intelligence, ego. They are all material. Mind is also material, intelligence is also material, but they are subtle forms. And spiritual existence is the living entity, as we are. These things are very nicely explained in the Bhagavad-gītā. Apareyam itas tu viddhi me prakṛtiṁ parām. The material, physical elements, they are inferior quality of . . . inferior quality, energy, of Kṛṣṇa. But the superior quality of energy we are, living entities. Jīva-bhūtāṁ mahā-bāho yayedaṁ dhāryate jagat (BG 7.5).