Mind is a very common word, but as a concept, it contains far more than is ordinarily understood. Neither in the Western philosophy nor in science do we have a satisfying definition of what Mind is. Indian philosophy and spirituality that know all about mind and its extraordinary capacities do not seem to have defined mind.
European languages have grown so much that every shade of thought and feeling has an appropriate word. Memory is one faculty of mind whose star performance startles others. The word 'understanding' has a nice distinction from 'thinking', in that one is a faculty and the other is the product of it. Judgement, decision, discretion, discrimination, observation, determination and many other faculties go to make what we know of Mind.
We know of running thoughts in the mind which is generally mistaken for thinking. It stops in meditation. Thinking is a serious process which constantly coordinates thoughts. After the running thoughts fall quiet, thinking will be there in its full force. One can notice an OBSERVER that is distinctly different from the thinker. One faculty of the observer is to pass comments non-stop and maintain a second line of thought in the mind. Sri Aurobindo called this faculty censor, which will be the last to fall quiet or die.
Silence reigns in the mind when the censor withdraws from its incessant action. Invocation of Spirit has many levels of effectivity. Conquest of the censor is the complete victory in this line of action. Jnana Yoga conquers thoughts, Raja Yoga's overlordship is over the entire Mind. There is a Spirit at each level, or the powers of the Spirit are of several grades. That Spirit which silences the censor secures a consummate victory over Mind.