I came across an interesting (and useful!) bit of Unix history – an explanation for the vi navigation. Until now all I knew was that HJKL keys were on the home row for those who touch type. Apparently, there is more to that. ADM-3A terminal which was used to create the original vi had the actual navigation arrows printed on the keyboard. Here is a photo of how it looked:
Read the original post that also demonstrates why the Escape key was chosen for mode changing, and also why ~ is used for home directory in Unix operating systems.