Really good question. To know it would be great as that is what one can visualize and focus stable attention on and thus receive much internal benefit from. I don't know the absolute best, and maybe there is not an absolute best, it could vary between stages. I definitely know that a good start is to use the image of the Sun to meditate on. Please do leave in the comments section what you think may be the best image for inner development to meditate on. End (5917).
Make knowledge consciousness. Acting now makes knowledge consciousness. As the consciousness is now. Light is consciousness. Light can transform darkness. Light shining in the darkness brings change. In change there is joy. Knowing and using the light is Gnostic wisdom.