TL;DR

I had my mind blown discovering the beautiful digitization of Euclid’s Elements.

Without further ado:

The First Six Books of The Elements of Euclid With Coloured Diagrams and Symbols

What is this about?

The site has it:

A reproduction of Oliver Byrne’s celebrated work from 1847 plus interactive diagrams, cross references, and posters designed by Nicholas Rougeux

Is it easy?

Well… yes and no. If you’re used to math symbolism (as I assume to be), you’ll have to re-learn it in favor of shapes and colors.

One thing that puzzled me a bit was the Pythagora’s Theorem demonstration (i.e. Proposition XLVII), when it says that the area of the red square is twice the area of a specific triangle - the following picture shows it:

Step I stumbled on in Pythagoras's theorem demonstration

After sweating a bit, and looking in Google, it was clear that the square and the triangle share both the same base and the same height, hence their areas’s ratio must be two.

So long!

What to say more? Go take a look, it’s amazing! Be sure to click on the pictures in the demonstrations, they will highlight stuff in the pictures on the side (where it makes sense), making it awesomely comfortable to follow.