“Of all things the measure is Man, of the things that are, that they are; and of the things that are not, that they are not.”

-Protagoras, fragment 80 (the Homo Mensura fragment) 

“Through logos humanity truly is the measure of everything. Only that which can be experienced as something is, and that which can not be thus experienced is not.”

-Mats Rosengren's updated, clearer version of Protagoras' fragment 

‘When a cave supports a mountain on rocks deeply eroded from within, not made by human hand, but excavated to such size by natural causes, your soul is seized by a religious apprehension.’

-Seneca, quoted in Caves and the Ancient Greek Mind by Yulia Ustinova (2009)

“Genuinely, we know nothing: the truth is in the depth”

-Democritus, fragment 117