In plain words
When he set about arguing with his guru, Śaṅkara stayed in the utmost humility and obedience. ‘Vidyāvinayasampanne.’ That is, for a student humility alone is the ornament. Without humility, learning does not come to us. Before he set about debating with the guru, he bowed to the guru and prayed, ‘Give me leave to debate with you.’ Taking the guru's permission, he began the debate with the guru himself. In this debate he refuted the guru's statements most wonderfully, never going against the Śāstras, never running counter to the Vedas, never departing in any way from the material, worldly paths, and he went on teaching clearly the marks of pravṛtti within the path of nivṛtti. In former times there were great, great paṇḍitas. But they forgot the truth that learning is for Jñāna alone. Even today students think that learning came into being for the sake of bread. No, this is a great mistake. ‘Labour is for bread, learning is for Jñāna.’ Śaṅkara had recognised this truth: how was he to set these paṇḍitas on the path? Great as they were, though they had learned all the learning they could want, they were misusing it, they were putting it to no use. He went to great pains to bring them onto the right path.
From rising out of sleep until you go to sleep again, for the belly's sake, you let your life run to waste without limit or reckoning; you pour it out on your learning, forgetting the Lotus-eyed One: what great happiness have you gained? Think it over gladly, O man! ‘I have read the books, I have looked through all the Śāstras, I have learned learning without equal,’ you say: why this pride? With your two hands joined you cannot worship the Paramātma with Bhakti; these present-day learnings are every one of them ruinous learning: see it, O man!