2.66 Ayuktasya, for the unsteady, for one who does not have a concentrated mind; na asti, there is no, i.e. there does not arise; buddhih, wisdom, with regard to the nature of the Self; ca, and; there is no bhavana, meditation, earnest longing [Longing to have a continuous remembrance of the knowledge of Brahman which arises in the mind from hearing the great Upanisadic sayings (maha-vakyas).] for the knowledge of the Self; ayuktasya, for an unsteady man. And similarly, abhavayatah, for an unmeditative man, who does not ardently desire the knowledge of the Self; there is no santih, peace, restraint of the senses. Kutah, how can there be; sukham, happiness; asantasya, for one without peace? That indeed is happiness which consists in the freedom of the senses from the thirst for enjoyment of objects; not the thirst for objects  that is misery to be sure.
The implication is that, so long as thirst persists, there is no possibility of even an iota of happiness!
It is being stated why a man without concentration does not possess wisdom: