Philosophy is the survey of all the sciences with the special object of their harmony and of their completion. It brings to this task not only the evidence of the separate sciences but also its special appeal to the concrete experience – Whitehead
Vidya and Avidya, the Self and the not-Self, as well as sambhūti and asambhūti, Brahman and the world, are basically one, not two. Avidya affirms the world, as a self-sufficient reality. Vidya affirms God as the Other, as a far away reality. When true knowledge arises, says the Upanishads, this opposition is overcome.
The true knowledge involves comprehension of the total Reality, of the truth of both Being and Becoming. Philosophic knowledge or vision cannot be complete if it ignores or neglects any aspect of knowledge or experience. Philosophy is the synthesis of all knowledge and experience, according to the Upanishads and according also to modern thought. Brahmavidya, philosophy, is sarvavidyapratishthā, the basis and support of all knowledge, says the Mundaka Upanishad. All knowledge, according to that Upanishad, can be divided in to two distinct categories – the apara, the lower, and the para, the higher. It boldly relegates all sciences, arts, theologies, and holy scriptures of religions, including the Vedas, to the apara category. And that is para it says, yayā tadaksharam adhigamyate, by which the imperishable Reality is realized.’
The vision of the Totality therefore must include the vision of the para and the apara aspects of Reality. If brahmavidya, philosophy, is the pratisthā, support, of sarvavidyā, totality of knowledge, it must be a synthesis of both the aparā and the parā forms of knowledge.
This is endorsed by the Gita in its statement that the jnana, philosophy, is the synthesis of the knowledge of the not-Self and the Self:
क्षेत्रक्षेत्रज्ञयोर्ज्ञानं यत्तज्ज्ञानं मतं मम ।
kṣetrakṣetrajñayorjñānaṃ yattajjñānaṃ mataṃ mama |
The synthesis of the knowledge of the not-Self, avidya, which is positive science, with that of the Self, vidya, which is the science of religion, will give us true philosophy, which is the knowledge flowering in to vision and maturing into wisdom.
This is purnajñāna, fullness of knowledge, as termed by Ramakrishna. The Gita speaks of this as jñānam vijñāna sahitam — jñāna coupled with vijñāna, and proclaims this as the summit of spiritual achievement:
बहूनां जन्मनामन्ते ज्ञानवान्मां प्रपद्यते ।
वासुदेवः सर्वमिति स महात्मा सुदुर्लभः ॥
bahūnāṃ janmanāmante jñānavānmāṃ prapadyate |
vāsudevaḥ sarvamiti sa mahātmā sudurlabhaḥ ||
‘At the end of many births, the wise man attains Me with the realization that all this (universe) is Vasudeva the indwelling Self); such a great-souled one is rare to come across’