Sometimes it is easier to understand concepts with images, always remembering that they are only metaphors pointing to something beyond. 

Archetypal images, as universal patterns or motifs which come from the collective unconscious, are the basic content of religions, mythologies, legends and fairy tales. Link

 

Useful links:

The seal of the Theosophical Society

Ancient Symbols

 

Sacred Geometry Symbols And Their Meanings – The Extensive List