Socrates said that a man can discover the truth by himself if you "question him rightly." It can be assumed by that statement that if you ask right questions you can elicit the truth to come out. This presupposes that the truth lies inside of the person being asked already, and the great gad-fly's job is that of a guide. This clearly demonstrates the universality of Truth, and yet how do we reconcile such implication to our modern belief in cultural relativism, which assumes that truth is a mere byproduct of a culture?
And Socrates' calling in life was to awaken people to knowledge of Truth through self-examination, which only humans are capable of. Socrates was the best of Athenians because he had a knowledge of his ignorance of this Truth, and yet people around him did not have this knowledge, but rather they were proud and showy of their supposed knowledge and wealth, completely unaware of their inner persons.