Thales: presocratic, explaining reality, made of water, first to take philosophical approach

Anaximander: presocratic, reality was boundless

Anaximenes: presocratic, air is the source of things, similar to Thales

Empedocles: presocratic, matter was made up of the 4 elements

Heraclitus: presocratic, reality is changing

Democritus: western materialism, everything consists of atoms and empty space

Pythagoras: influential math thinker, believed everything derived from numbers

Xenophanes: presocratic, suggested one god who was not anthropomorphic, or a god who did not imitate human qualities.

Parmenides: presocratic, change is an illusion, founded Eleatic school

Zeno of Elea: presocratic with Parmenides, change is an illusion

Gail Stenstad: feminist philosopher, anarchic thinking

Victor Frankl: a Jewish philosopher who saw humans as ultimately free beings

Mohandas Gandhi: jain philosopher, knowledge predates senses