Samuel Johnson wrote his Preface to Shakespeare for his annotated edition of The Works of William Shakespeare, which Johnson published in 1765. Since then, Johnson's preface has been celebrated as an astute work of literary criticism and valued for its insights into understanding Shakespeare. While contemporary readers acknowledge Johnson's prejudices, they still value his methodology and central conclusion.

What sets Johnson's methodology apart from others of his time, setting a precedent for literary criticism throughout the ages, is comparison. By comparing Shakespeare to other playwrights, both classic and contemporary for Johnson's time, Johnson was able to analyze Shakespeare in a new way. In particular, he was able to distinguish what Shakespeare had borrowed and what he had created himself. This method of intense research and comparison has become a model for all literary criticism today.

One of Johnson's most influential conclusions is that Shakespeare is timelessly valuable because of his ability to understand and characterize human nature. Johnson's conclusion about Shakespeare's worth is best summed up in his following statement: "This therefore is the praise of Shakespeare, that his drama is the mirror of life." What he means in saying this is that Shakespeare's characters mirror real people through their real thoughts, real feelings, and real actions. As Johnson further states, Shakespeare's characters are not limited to the time in which they were created or by their cultures or ethnicities because "they are the genuine progeny of common humanity, such as the world will always supply, and observation will always find." Hence, according to Johnson, Shakespeare's value lies in the fact that he created genuine human characters that all of humanity can relate to across the ages.