I have taken to writing a few answers on Quora, a website I like for its good manners and serious interest in disseminating information and understanding. I have had a few upvotes for some of my answers and am trying to do better. Today I answered a question about ethics and values and managed to keep it briefer than usual. This is more or less what I wrote.
Kant had four great questions, although the fourth is sometimes forgotten. 1. What can I know? 2. What ought I to do? 3. What may I hope for? 4. What is man?
It seems to me that the greatest philosophers, Plato, Kant, Wittgenstein for example, are concerned above all with what it is to lead the life of a decent human being. And because it is clear that their thought and conduct were of a piece, in a word, that they had integrity, their lives and writings had an impact on those who knew them. Socrates provided an inspiring example to Plato which informed his whole life, even if his philosophy went far beyond that of Socrates in breadth and complexity; and Wittgenstein gathered round him a small group of sympathetic friends, many of whom, although not all, were professional philosophers. They are often referred to as disciples, and this seems the obvious and natural word to describe them, since his influence on them was so profound. Anyone who has been fortunate enough to receive the love of an involved and generous parent or to encounter a great teacher, will know that the meeting with a wonderful human being leaves a lasting memory. But what one also learns from such formative relationships is that the most powerful teaching of ethics comes through the example of good people, although reflecting on the nature of good behaviour is an important activity as well.
What is man? My non-answer is: a spiritual being.