Iṣṭa-devatā

"cherished deity", a worshipper's favourite deity, the form of God which inspires them the most.

yidam, a deity that you yourself have chosen. this deity has no existence, it's a picture. it's to put in your mind the idea of a deity and it will achieve life insofar you make this your deity. and then this deity becomes your guide for your life. this happens to be mine (deity of reading). everything i know i got it from reading. and when i meet buddhas, yogis and what not, i interpret them in terms of my reading. i put this in front of the buddha himself and this is what holds you. other people would have other chosen deities. but stick to your chosen deity. it's your way. and the whole buddha world will come to your knowledge through whatever your deity is.

i call these the most sophisticated notion of deity that i know. the notion of a chosen deity that is going to be your guide.

Joseph Campbell

Hinduism teaches Ekam Sadvipraha Bahudha Vadanti, "While Truth is One, the Names are Many".