Aristotle identifies approximately eighteen virtues that enable a person to perform their human function well.[14] He distinguished virtues pertaining to emotion and desire from those pertaining to the mind.[15] The first he calls "moral" virtues, and the second intellectual virtues (though both are "moral" in the modern sense of the word). Each moral virtue was a mean (see golden mean) between two corresponding vices, one of excess and one of deficiency. Each intellectual virtue is a mental skill or habit by which the mind arrives at truth, affirming what is or denying what is not.[16] In the Nicomachean Ethics he discusses about 11 moral virtues: