Monads are ...

Boxes full of fruit
And a fruit to fruit transformer
That takes apples from the box
And spits out a box of berries

Nuclear waste containers
Filled with sludge to be disposed of
And sludge disposal robots
That dispose of waste containers

Programming language macros
Producing text from other text
And of all the text producers
Nothing's cooler than a macro

Scared and helpless creatures
And some predatory monsters
Who devour the sad creatures
And destroy them through digestion

Brave and weightless humans
Floating in and out of spaceships
Whose blood would quickly boil
Were it not for helpful spacesuits

Assembly line transmuters
Push and popping trays
Full of many objects
To be combined in many ways

I guess we had better stop
Before this thing goes off the rails
Like an engine pulling cars
Filled with monad tutorials