Fantasy

Talk about a totally acid trip. Prehistoric man knew nothing but, what he/she believed in hence: Religion.

 Early man/woman experimented in everything that it could learn from. That including any and all hallucinations he/she could chew.

[The image depicts a man peering through the Earth's atmosphereas if it were a curtain to look at the inner workings of the universe. The caption translates to "A medieval missionary tells that he has found the point where heaven and Earth meet..."]