'If you put me to death,' Socrates warned his Athenian judges, 'you will not easily find anyone to take my place.' So indeed it would prove, a single cup of hemlock robbing the western philosophical tradition of the man with best claims to be its founding father.

Yet Socrates' influence was not so easily to be done away with. His words lovingly recorded by his devoted disciple Plato, his doctrines reached a posterity which has, through twenty-seven centuries now, taken him as its teacher.

The marriage of idealism and scepticism in his though; his sense of education as self-discovery; his view of philosophy as preparation for life: these have been the stuff of western thought at its best. So completely did Socrates embody these values, he was prepared to die in their defence...