I have long argued that everyone should read the original works. The case of E = mc² is a great example. Read the original paper...just 4 short pages! See how Einstein's brain actually worked. It is truly awe inspiring. He pulled truth out of imagination with perfection. Here you go! Have fun!

https://www.fourmilab.ch/etexts/einstein/E_mc2/www/

Truth is everywhere, just lurking. Descartes (50 years before Newton) noted in science that no matter what we know today, there will always to be more to know. It is how the human brain computes reality.