May 16

O thou handmaid of God! It is recorded in eastern histories that Socrates journeyed to Palestine and Syria and there, from men learned in the things of God, acquired certain spiritual truths; that when he returned to Greece, he promulgated two beliefs: one, the unity of God, and the other, the immortality of the soul after its separation from the body; that these concepts, so foreign to their thought, raised a great commotion among the Greeks, until in the end they gave him poison and killed him.

And this is authentic; for the Greeks believed in many gods, and Socrates established the fact that God is one, which obviously was in conflict with Greek beliefs. 
(‘Abdu’l-Baha, ‘Selections from the Writings of ‘Abdu’l-Baha’)