Sanity refers to the soundness, rationality, and health of the human mind, as opposed to insanity. A person is sane if they are rational. In modern society, the term has become exclusively synonymous with compos mentis. The contrast is non compos mentis, or insanity. According to the writer G. K. Chesterton, sanity involves wholeness, whereas insanity implies narrowness and brokenness.
A sane mind is nowadays considered healthy both in its analytical and emotional aspects. From Wikipedia
