April “opens” summer and while you may have thought its on-again off-again weather is the impetus for the April Fool’s Day tradition, the origins are actually so old no one knows where it really started.  But if you read the excerpt pictured below, I think I may have found why we call people who are easily fooled “a fish.”

I think it may be appropriate that the entry for April comes after that of Aquarium.

From my Grandparent’s A volume of Compton’s Pictured Encyclopedia, 1937 edition: