Mind refers to the collective aspects of intellect and consciousness which are manifest in some combination of thought, perception, emotion, will and imagination.
There are many theories of what the mind is and how it works, dating back to Plato, Aristotle, Adi Shankara, Siddhārtha Gautama, and other Ancient Greek and Indian philosophers. Pre-scientific theories, which were rooted in theology, concentrated on the relationship between the mind and the soul, the supposed supernatural, divine or God-given essence of the human person. Modern theories, based on a scientific understanding of the brain, see the mind as a phenomenon of psychology, and the term is often used more or less synonymously with consciousness.
The question of which human attributes make up the mind is also much debated. Some argue that only the "higher" intellectual functions constitute mind: particularly reason and memory. In this view the emotions - love, hate, fear, joy - are more "primitive" or subjective in nature and should be seen as different in nature or origin to the mind. Others argue that the rational and the emotional sides of the human person cannot be separated, that they are of the same nature and origin, and that they should all be considered as part of the individual mind.
In popular usage mind is frequently synonymous with thought: It is that private conversation with ourselves that we carry on "inside our heads." Thus we "make up our minds," "change our minds" or are "of two minds" about something. One of the key attributes of the mind in this sense is that it is a private sphere to which no one but the owner has access. No-one else can "know our mind." They can only know what we communicate.