The Irish mythological hero Finn MacCool is known for many exploits, from the slaying of a great fire monster to the creation of Giant's Causeway. However, he’s also known for his magical thumb, which he could suck on to gain knowledge. In this Stuff to Blow Your Mind two-parter, Robert and Joe consider the thumb of knowledge and its relations to other myths and even a little bit of science. (originaly published 03/17/2022)