The mind consciousness corresponds to theory, while the manas corresponds to realization

How can we prove that the mind consciousness operates at the level of learning knowledge and theory, while the manas operates at the level of realization? Take cooking as an example of a dharma: first, the mind consciousness must learn the theory and techniques of cooking. But having learned the theory does not mean one can actually cook. With respect to the dharma of cooking, this shows that it has not yet been realized. 

Then how is it to be realized? One must personally practice cooking. Practicing cooking belongs to actual operation, and actual operation requires the manas to direct and supervise. If the manas does not understand the theory, it cannot supervise the six consciousnesses in cooking. Thus the manas must repeatedly direct the six consciousnesses to practice cooking. When something is done incorrectly, the mind consciousness must then contemplate and analyze what went wrong and how it should be done—this is the mind consciousness directing the manas to practice the operation.

Once the manas has learned the operation, the mind consciousness no longer needs to analyze and supervise much; the manas can then direct the six consciousnesses to cook with great proficiency, and thereafter will handle it with ease, with highly skilled technique. "Like driving a light cart on a familiar road"—this describes the level of skill mastered by the manas. 

Therefore it is said: the mind consciousness corresponds to theory, while the manas corresponds to actual operation. The theory known by the mind consciousness is of little use; only after the manas has actually realized it does it become of great use. Personal realization refers to the manas personally realizing it, not to knowledge and theory that the mind consciousness has learned from elsewhere.