In plain words
It has two wings. But with two wings alone this aeroplane does not move. There must also be a tail to bring these two wings into harmony. Only through these three is the body in the middle kept in balance. Whether or not you have noticed it while sitting inside the plane, at the time of climbing one wing comes down. One wing goes up. At the time of coming down, the other wing comes down. Another wing goes up. That is, in the world of this life Satya comes first for us. Ṛta comes after it. When we make enquiry on the spiritual path, Ṛta comes first. Satya follows after it. So all this depends on a balance. Only when every kind of balance is right does this Buddhi take shape as Buddhi. Without Ṛta, Satya and yoga, this is no Buddhi at all.
What is this yoga? Is it kriyā yoga, or haṭha yoga, or rāja yoga? It is none of these. Merely doing āsanas is not yoga. This is a physical training. A kind of exercise. All these were made only for nourishing the body. True yoga is 'Yogaḥ cittavṛtti nirodhakaḥ': the yoga that restrains our senses is the true yoga. This very yoga is the tail. Only when it is joined with this yoga does the Buddhi move on the right path. One who has only the power of medhā and cleverness, him they call a man of Buddhi. That is no man of Buddhi, that! He may be a clever man. There, Buddhi should not be used. If Buddhi is to be used, where should it be used? Only at the time when these five come together, the inner śraddhā, Ṛta, Satya, yoga and Mahat-tattva, can the word Buddhi be used for it. Even when this yoga is there, the body is in the middle. That is the Mahat-tattva. The great principle. Mahat means great. Tattva means that which has recognised the two. That is why the great mantra said, 'Tat tvam asi.' 'That is I,' it says. The principle 'this divinity endowed with all power is I' is itself this Mahat-tattva. 'I am Sat-Cit-Ānanda': this is the Mahat-tattva. The good fortune of the vision of one's own true Self is this Mahat-tattva. To recognise for oneself who one is: that is the true principle.