In the derivation of the word insanity lies its definition. In English, the word sane derives from the Latin adjective sanus meaning healthy. The word insanity was first used in the 1550s. Naturally the word insane means unhealthy. From Latin insanus meaning mad, insane, then comes the root of in meaning not, in Latin. The phrase mens sana in corpore sano is often translated to mean a healthy mind in a healthy body. In law, mens rea means having had criminal intent, or a guilty mind, when the act was committed.
From this perspective, insanity can be considered as poor health of the mind, not necessarily of the brain as an organ. Rather it refers to defective function of mental processes such as reasoning. Back in early history, individuals believed that insanity began because of demonic possession, causing a lack of rational thought. Insanity is a mental illness and not triggered by a demonic possession. The word insane has now changed to specifically mean unhealthy in the mind rather than unhealthy overall. This does not mean the brain is unhealthy, but rather that the mind or process of reasoning has been impaired.
Becoming insane is a process that often