In plain words
Bhoktā devo maheśvaraḥ. That is, what is sprinkled into it is this: the food we eat must give lasting Ānanda. It is sprinkled in Ṛta and Satya. So: O You who are Brahmā, Viṣṇu and Maheśvara in form, You whose form is the three worlds and the knowledge of the three times, grant us the nature of Ṛta and Satya. Ṛta must be made to grow in us. That is, we must achieve trikaraṇa śuddhi. Satya must be in our conduct without cease. To turn food of this kind into Ṛta and Satya, they would sprinkle the food, sanctify it and receive it as prasāda.
But the men of today hold brain power alone to be the chief thing; forgetting this Ṛta and Satya, they strut about boasting that there is no power in this world beyond brain power. When Śaṅkarācārya was making his tour of conquest, a debate arose with Maṇḍana Miśra. This debate was to show what brain power is worth. There, someone had to have the authority to decide victory and defeat in the debates between the two of them. So they inquired who was to be the one to decide victory and defeat between Śaṅkarācārya and Maṇḍana Miśra. Having weighed it in every way, they appointed Ubhaya Bhāratī as judge to give the decision: she spoke Satya, she had a pure heart and a divine feeling, she had the wealth of Ṛta, she had śraddhā and steadiness. Buddhi means just this: Ṛta joined with these two, keen interest and steadiness; and that was the nature of this Ubhaya Bhāratī. Who was this Ubhaya Bhāratī? Maṇḍana Miśra's wife. When a debate is going on between Śaṅkarācārya and this Maṇḍana Miśra, would the opposite party anywhere in the world ask a man's own wife to decide who wins and who loses! Even if she did decide, she would want the victory to go to her husband's side; those who decide in equal-mindedness, in divinity, in purity are very rare. Then what was Śaṅkarācārya's nature? He chose that Ubhaya Bhāratī because he held the power of Buddhi to be far higher than brain power, far more powerful. So students must recognise that Buddhi is far more powerful than the intellect. This is not the Buddhi as it is commonly thought of. This Buddhi is the Śānti joined with āstha and svāstha, keen interest and steadiness. This Buddhi is the purity in which these two, Ṛta and Satya, are made one. Then again, yoga is a mighty power. Mahat-tattva: this Buddhi is the sanctity in which these two are joined.