In plain words
It is Manas that is the cause of man's living, of his bondage and of all his standing; Manas itself matters most for Mukti; Manas itself brings him to hell and makes him forget himself.
Students!
Man is the coming together of the body, Manas and the Ātma. These are the karmas, the steps that settle our feelings and take the inner being up to a higher level. What carries them out is the body. What comes to know is Manas. What is eternal, is Satya and is unceasing: that is the Ātma itself. This itself is the deity within man. Humanness is the manifestation of three powers: doing, knowing and being. Yet though Manas, the body and the Ātma give different results through different forms and go by different names, it is only by the oneness of these three that humanness attains divinity. The separation of these three is just what takes man down to the state of a beast. A word we often hear, in worldly matters and in spiritual ones, is 'antaḥkaraṇa'.
What is the antaḥkaraṇa? What is its form? What is its nature? What is special about it? What is its goal? When we enquire in this way, it is Manas itself that takes on many kinds of subtle forms and receives the name 'antaḥkaraṇa'. Manas, Buddhi, citta and Ahaṅkāra: these four shapes, too, are Manas itself. Buddhi, citta and Ahaṅkāra are only subtle forms of Manas. As it enters each kind of work, it takes a name for each. When one and the same brahmin is doing pūjā in a temple, they call him the priest brahmin. In the same way, when he is cooking in the kitchen, they call him the cook brahmin. When this very brahmin is teaching lessons to students, they call him the teacher brahmin. When he is reading out the almanacs, they call him the almanac brahmin. Though the brahmin is only one, he has come to have these names because of the occupations he follows.