LEGAL PRINCIPLE: A person is said to be of sound mind for the purpose of making a contract if, at the time when he makes if, he is capable of understanding it and of forming a rational judgment as to its effect upon his interests.
FACTUAL SITUATION: Mr. X who is usually of sound state of mind, but occasionally of unsound state of mind, enters into a contract with Mr. Y when he was of unsound state of mind. Mr. Y having come to know about this fact afterwards, wants to file a suit against Mr. X.