10. (It is) non-comprehensive.
The scriptural declaration does not refer to all meditations, but only to the meditation on the Udgîtha. In the clause 'what he does with knowledge,' the 'what' is in itself indefinite, and therefore must be defined as connecting itself with the Udgîtha mentioned in the previous clause, 'Let him meditate on the Udgîtha.' The sentence cannot be construed to mean 'whatever he does is to be done with knowledge,' but means 'that which he does with knowledge becomes more vigorous,' and that which is done with knowledge that is the Udgîtha. The next Sûtra refutes the argument set forth in Sûtra 5.