The human being shares the basic powers of the sensational thought-mind with animals. The ability to perceive and respond to impulses provided by the outer world is the first, most basic power of the Manas. Sri Aurobindo notes: “This natural action too has a double element, a physico-nervous impulse and behind it a mental-nervous power-value of instinctive will-impulse. That makes up the nexus of first perceptions and actions which is common to all developing animal life.”
Manas also has a basic element of the power of thought. “Just as the living body has a certain pervading and possessing action of consciousness, citta, which forms into this sense-mind, so the sense-mind has in it a certain pervading and possessing power which mentally uses the sense data, turns them into perceptions and first ideas, associates experience with other experiences, and in some way or other things and feels and wills on the sense basis.”
“This sensational thought-mind which is based upon sense, memory, association, first ideas and resultant generalisations or secondary ideas, is common to all developed animal life and mentality. Man indeed has given it an immense development and range and complexity impossible to the animal, but still, if he stopped there, he would only be a more highly effective animal. He gets beyond the animal range and height because he has been able to disengage and separate to a greater or less extent his thought action from the sense mentality, to draw back from the latter and observe its data and to act on it from above by a separated and partially freed intelligence. The intelligence and will of the animal are involved in the sense-mind and therefore altogether governed by it and carried on its stream of sensations, sense-perceptions, impulses; it is instinctive. Man is able to use a reason and will, a self-observing, thinking and all-observing, an intelligently willing mind which is no longer involved in the sense-mind, but acts from above and behind it in its own right, with a certain separateness and freedom. He is reflective, has a certain relative freedom of intelligent will. He has liberated in himself and has formed into a separate power the Buddhi.”
It is thus this further development of the reflective mind of reason and will, which clearly distinguishes the human mentality from the animal and takes the evolved human individual beyond the restrictions and limitations imposed by the sense-mind.
Sri Aurobindo, The Synthesis of Yoga, Part Four: The Yoga of Self-Perfection, Chapter 7, Purification–Intelligence and Will, pp. 637-638