“A close shave.”

In the past, student barbers learned to shave on customers. If they shaved too close, their clients might be cut or even barely escape serious injury. Today, we use this idiom if a person narrowly escapes disaster.

“Dot the i's and cross the t's.”

When only handwritten documents were used, it was very important for the clerk to write everything properly, especially letters like i and t, which could easily be confused. The idiom has since come to mean paying attention to every little detail.

“He who pays the piper calls the tune.”

In medieval times, people were entertained by strolling musicians. Whoever paid the price could choose the music. This proverb means that whoever pays is in charge.

“The pen is mightier than the sword.”

In seventeenth-century England, a free press was banned by the government. This meant that people who disagreed with the government and printed their views were punished. In spite of this, people published their ideas and opinions in illegal pamphlets that were distributed to the public. The proverb means that the written expression of ideas cannot be stopped by physical force