What, if any, are the marks of the mental? Does the mental have essential properties? Are the varieties of what is mental linked only by overlapping relations of similarity? Are these questions primarily about the marks of minds or about the marks of mental acts, states and dispositions? Attempts to answer these questions are to be found in the two main twentieth century traditions of early descriptive psychology and phenomenology and of analytic philosophy of mind. According to one unusual answer, mental items and psychological items differ essentially. A version of this answer is outlined and its compatibility with some accounts of love, hate and understanding examined.