The seemingly flippant question of how many angels can dance on the head of a pin has historical roots in the Middle Ages. The question is alternately asked, “How many angels can dance on the point of a needle?”
How many angels can dance on the head of a pin? was a serious topic of discussion among the scholastics. Thomas Aquinas said that, since two angels cannot be at the same place at the same time, then only one could be on the point of a needle at any given time. And the debate began. Others pointed out that angels are spirits, so there is no limit to the number that could fit on the point of a needle or the head of a pin. Of course, if angels are spirits, it might be wrong to consider them as being “on” anything. Looked at another way, if angels assume bodily form (as they do from time to time in Scripture), how small could they make themselves? A modern-day thinker might ask, if angels are as small as a bacterial cell, how many could fit on the head of a pin or the point of a needle? And could they make themselves even smaller than that? Could they make themselves as small as electrons? Even smaller than that? How many angels could fit on an electron?, etc., ad infinitum ad absurdum.
With the Reformation, Protestant theologians mocked this kind of speculation and debate. Why would theologians debate such issues when there were the important issues of salvation and eternity at stake? How a person can be made right with God is far more important than how many angels can fit in a small space. The question itself, evocative of impractical debates, has become an idiom referring to any type of unimportant academic discussion.
That’s why, today, if a person asks a theological or philosophical question that the hearer thinks to be a waste of time, he may express that opinion by answering the question with the question “How many angels can dance on the head of a pin?”
The original intent of the question of how many angels can dance on the head of a pin was not to determine the actual answer. The medieval scholastics were contemplating the nature of angels, spirits, physical space, and other theological and philosophical concepts. Such contemplations may indeed be valuable if they contribute to a greater understanding of biblical truth and are not ends in themselves. Even accurate biblical knowledge is not an end in itself. Jesus rebuked the religious experts of His day: “You study the Scriptures diligently because you think that in them you have eternal life. These are the very Scriptures that testify about me, yet you refuse to come to me to have life” (John 5:39–40).