Verse 6.7.3

तं होवाच यथा सोम्य महतोऽभ्या हितस्यैकोऽङ्गारः खद्योतमात्रः परिशिष्टः स्यात्तेन ततोऽपि न बहु दहेदेवंसोम्य ते षोडशानां कलानामेका कलातिशिष्टा स्यात्तयैतर्हि वेदान्नानुभवस्यशानाथ मे विज्ञास्यसीति ॥ ६.७.३ ॥

taṃ hovāca yathā somya mahato'bhyā hitasyaiko'ṅgāraḥ khadyotamātraḥ pariśiṣṭaḥ syāttena tato'pi na bahu dahedevaṃsomya te ṣoḍaśānāṃ kalānāmekā kalātiśiṣṭā syāttayaitarhi vedānnānubhavasyaśānātha me vijñāsyasīti || 6.7.3 ||

3. The father said to Śvetaketu: ‘O Somya, from a blazing fire, if there is but a small piece of ember left, the size of a firefly, it cannot bum anything bigger than that. Similarly, O Somya, because only one small part of your sixteen parts remains, you cannot remember the Vedas. Eat something and then you will understand what I am saying’.

Word-for-word explanation:

Tam ha uvāca, he said to him [to Śvetaketu]; somya, O Somya; yathā, as; mahataḥ abhyāhitasya, of a big blazing fire; ekaḥ aṅgāraḥ, one ember; khadyotamātraḥ, the size of a firefly; pariśiṣṭaḥ syāt, that is left; tena, by that; tataḥ api bahu, anything larger than its size; na dahet, cannot bum; evam, like that; somya, my son; ekā kalā, only one part; ṣoḍaśānām kalānām, of [yourl sixteen parts; atiśiṣṭā syāt, has remained; etarhi, now; tayā, by that [small part]; vedān, the Vedas; na anubhavasi, you do not remember; aśāna, eat; atha, then; me, my [words]; vijñāsyasi iti, you will grasp.

Commentary:

Suppose you have a big pile of wood, and you start a fire with it. After awhile practically the whole pile is consumed, and there is only a small spark left—a spark as small as a firefly. Very little can be burnt with such a tiny spark, yet even so, if you add some fuel to it you can again start a big fire.

‘Similarly,’ Uddālaka says to his son, ‘your mind is like that tiny spark. It is not functioning now because you have not given it any fuel these last fifteen days. There is just a flicker of your mind working, and it cannot serve any useful purpose. If you eat something now, everything will come back to your mind.’