If someone were to invent a time machine, these are the people that would be worth having a chat with.

Before any other wise man or woman came they. The sages of the ancient times have inspired and taught in an age when spirituality wasn't a semi-common 'household item'. They were the true revolutionaries. Anybody seeking the universal truth (or truths) would do well to first and foremost familiarize themselves with these thinkers and their wisdom. The order in which they appear is the order in which they were born.

Imhotep

~2900 BCE

Akhenaten

~1300 BCE

Lao Tzu

600-470 BCE

Mahavira

599 - 527 BCE

Pythagoras

570-495 BCE

Buddha

563-483 BCE

Confucius

551-479 BCE

Socrates

~469 - 399 BCE

Plato

~427 - 348 BCE

Aristotle

384 - 322 BCE

BCE... Before Common Era