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

Symbols connect us to transcendent ideas, as the etymology suggests:
Latin symbŏlus, from the Greek sýmbolos, formed by the prefix sin-, given the Greek articulation syn-, that points out the idea of ‘meeting, encounter or union,’ from the Indo-European reference *sun-, contemplated as the connector, and – bolus detached from the verb ballein, that refers to ‘throwing’ or ‘casting’, with roots in the Indo-European *gwele-, for ‘throwing’.

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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

https://www.ancient-symbols.com/

https://symbolsandmeanings.net/sacred-geometry-symbols-meanings-list/