Machine learning has revealed exactly how much of a Shakespeare play was written by someone else

For much of his life, William Shakespeare was the house playwright for an acting company called the King's Men that performed his plays on the banks of the River Thames in London. When Shakespeare died in 1616, the company needed a replacement and turned to one of the most prolific and famous playwrights of the time, a man named John Fletcher. Fletcher's fame has since quelled. But in 1850, a literary analyst named James Spedding noticed a remarkable similarity between Fletcher's plays and passages in Shakespeare's Henry VIII. Spedding concluded that Fletcher and Shakespeare must have collaborated on the play.