Kena Upanishad 2.p3

2.p3

nanviṣṭaiva suvedāham iti niścitā pratipattiḥ|

Prāṇena, by the organ of smell, produced from earth, existing in the nostrils, and associated with the activities of the internal organ and the vital force; yat, that which; man na prāṇiti does not smell, does not comprehend like smell; yena, that by which light of the Self; prāṇaḥ, the organ of smell—being illumined as an object; praṇīyate, is impelled—towards its own object. All the rest, tat eva etc., is just like what has gone before.

Objection: Is not such a firm conviction as, "I know well enough", desirable?