Whenever I use the Web with all it's wonders, all the information I get for free (give or take a few adds and ignoring cross site cookies traking my data) I am very grateful towards Tim Berners-Lee for making this modern miracle possible.
Whenever I can spend hours in a library reading fascinating books, exploring new worlds born from the imagination of other human beings and having insightfull (although rather one-way) conversations with brilliant minds who have long been dead, I am grateful towards Johannes Gutenberg.
But the person, the historic genius, (or rather persons) that I am most grateful towards comes to my mind when I am playing with my dog: the unknown members of a stone age tribe or tribes who came up with the idea of taming wolves all those tens of thousands of years ago.
Thank you so much!