[petepete]

> mention how long the bricks were made before then to quickly understand the length of the pre-instruction era

Worth mentioning that Lego lifted the idea from Kiddicraft. Hilary Page patented Self-Locking Building Bricks in 1939 but had committed suicide by the time Lego brought their product to the UK.

https://www.hilarypagetoys.com/Home/Products/39/0

[bonzini]

True, but adding the hollow tube to the bottom side greatly improved how much the bricks stuck together, compared to Kiddicraft. It's not a small change.

Lego also tried other designs like crosses on the bottom but then kept the tube (and later the filled small tube that you can see on 1xN bricks and plates).