Montaigne may not have invented the essay but he certainly coined the term, giving it as the title to his Essays, from the French word meaning "attempt." He tackled subjects large and small, from death and religion to the lowly thumb. (Interestingly, journalists often refer to a wooly think piece as a "thumbsucker.") Montaigne took a scholarly approach to the subject of thumbs, complete with Latin citations and a reference to Tacitus, who reported that barbarian kings would prick their intertwined thumbs and suck them to make a blood oath. Montaigne also noted that the Romans exempted from military service all those with injured thumbs, which led some reluctant warriors to cut them off entirely to avoid combat duty.
The thumb is not only handy for wielding a sword but also a pen -- and of the two, the pen is generally regarded as the mightier. One can image Montaigne casting about for some fit topic to tackle in one of his essays and his eye alighting on the object closest at hand, the appendage that held his pen in place as his fingers danced across the page. In his essay, Montaigne neglects to mention the thumb's most distinctive feature. Of all God's creatures, only a handful have an opposable thumb capable of grasping an object, and only human beings make use of this capability to put pen to paper. Never mind that the evolutionary advantage of an opposable thumb probably came from being able to wield a sword (or club) rather than a pen.
According to Scripture, we are made in God's image. Taken literally, this would suggest God also has thumbs, which stands to reason. The Bible tells us that God created the world, but it never explains exactly how. It is one thing to have the idea and quite another to take it in hand. Where would a Da Vinci or a DeBakey be without thumbs? For that matter, where would Montaigne be? Without a thumb to set pen to paper, his thoughts on the subject would have been lost to the ages.