During the middle ages, monks made little illustrations or notations in the margins of manuscripts. The technical term for this kind of doodling is marginalia. It's not the main illustrations. They are doodles done in the margins. 

These manuscripts are somehow connected to sketchnoting because they are books written by hand 'manu' means hand; 'scriptus' means to write. They are not printed books."

You can incorporate specific characteristics about these provocative drawings to take your visual metaphors to the next level. 

1) Blend to drive attention. 

Today, we use a highlighter marker to draw attention to a key piece of text we are reading. But back in the Middle Ages, when they wanted to highlight something, they drew a little symbol called the manicule. Which in Latin means 'little hand.' As you can see in these drawings, they were not just hands many times. They blended these hand symbols with something else to add an extra hook to highlight and...