Over four hundred years after his death (on April 23), William Shakespeare (1564–1616) remains the most widely read author of all time. If he were alive today, he might boast of having sold between 2 and 4 billion copies of his plays and poems in all corners of the world.

His books are still an important part of the high school and college curricula, and not just in English, drama, or literature courses. It is perhaps a fitting testament to the Bard’s versatility that he is read in classes that have little in common with arts or linguistics—such as biology, economics, law, and psychology.

For instance, according to this recent article, The Tempest is the most often assigned reading in biology classes, Timon of Athens in economics, Hamlet in psychology, and The Merchant of Venice in law (interestingly, Henry VI, which includes the famous line: “The first thing we do, let’s kill all the lawyers” does not figure in law classes’ curriculum).

The reason Shakespeare’s works have such an enduring appeal—and provide teachable moments to people from different walks of life and fields of study—is that he wrote about human nature in all its forms. Even today, themes such as love, honor, bravery, ambition, murder, political intrigue, and betrayal are as relevant and relatable as they were back in the Elizabethan era.

In terms of longevity, Shakespeare’s legacy is still very much present in our lives, which brings to mind this line from his play Antony and Cleopatra:  “I have Immortal longings in me.”

In fact, the topic of immortality, along with Shakespeare’s belief in the durability of his works, is the main theme of two of his Sonnets (18 and 55). In the latter one, he wrote: “Not marble, nor the gilded monuments of princes, shall outlive this powerful rhyme.”

So far, at least, history has proven him right.