Conversation so far:
What was his relationship with Cosmology?
There is no one single authoritative account of the creation of the cosmos, but rather a series of several accounts.
What were some of the accounts?
In these texts, instead of a large pleroma, there is a discrete division between light and darkness.
What divides them?
The ruler of darkness is called Ptahil (similar to the Gnostic Demiurge), and the originator of the light.
Can you elaborate on this?
When this being emanated, other spiritual beings became increasingly corrupted, and they and their ruler Ptahil created our world.
Around what time were these theories created?
CANNOTANSWER.
Are there any other interesting aspects about this article?
The name Ptahil is suggestive of the Egyptian Ptah--the Mandaeans believe that they were resident in Egypt for a while--joined to the semitic El, meaning "god".
Why do they believe that?
CANNOTANSWER.

Question: How did cosmology effect the way they lived?
Self-contained rewrite: How did cosmology effect the way the Mandaeism believers lived?