Brahma Sutras – According to Shankara 3-3-21
Topic 21 - Muṇḍaka 3.1.1 and Katha 1.3.1 form one Vidyā
इयदामननात् ॥ ३४ ॥
iyadāmananāt || 34 ||
iyat-āmananāt—On account of describing as this much.
34. Because (the same thing) is described as such and such.
“Two birds of beautiful plumage . . . one of them eats the sweet and bitter fruits thereof, the other witnesses without eating” (Mu. 3. 1. 1).
Again we have, “There are the two . . . enjoying the results of their good deeds” etc. (Kath. 1. 3. 1).
In these two texts do we have two different Vidyās, or one only?
The opponent holds that these are two Vidyās, for unlike the meditation on the Immutable, where the object of meditation was one, as shown in the previous Sutra, here there are different objects of meditation.
That it is so is clear, for of the texts cited above, the Muṇḍaka text says only one eats the fruit, while the other does not; in Katha, however, both of them enjoy the results of their good actions. So the object of meditation is not identical.
The Sutra refutes it and says that they form one Vidyā, for both describe the same Lord as existing thus and thus, i.e. in the form of the Jīva.
In other words, the object of the two texts is to teach about the Supreme Brahman and show the identity of the Jīva and Brahman.
It has been explained in 1.2.11 that the Supreme Lord does not actually enjoy the fruits of actions, but is said to do so because of His being mentioned along with the Jīva, which does, as when we say, ‘The men with the umbrella’, where only one of them has the umbrella.
Therefore the object of the meditation being one, the Vidyās are also one.