Which writer created the opening quote for Alfred Hitchcock's 1945 film "Spellbound"?

The movie "Spellbound" (1945) an American psychological thriller film directed by Alfred Hitchcock, and starring Ingrid Bergman, Gregory Peck, and Michael Chekhov, opens with a William Shakespeare quote from the play “Julius Caesar”. Before giving a handy tutorial in mental illness and psychoanalysis, the quote, "The fault… is not in our stars, but in ourselves…” is provided.

In the film itself, it follows a psychoanalyst who falls in love with the new head of the Vermont hospital in which she (Bergman) works. She so learns that the doctor, this psychoanalyst (Peck), is an imposter suffering dissociative amnesia, and potentially, could be a murderer.

William Shakespeare (baptized April 26, 1564, Stratford-upon-Avon, Warwickshire, England—April 23, 1616, Stratford-upon-Avon) was a poet, dramatist, and actor. He was also called the English national poet and considered by many to be the greatest dramatist of all time. It has been said that no other writer’s living reputation can compare to that of Shakespeare, whose plays, written in the late 16th and early 17th centuries for a small-scale repertory theatre, are now performed and read more often and in more countries than ever before. The prophecy of his great contemporary poet and dramatist, Ben Jonson, that Shakespeare “was not of an age, but for all time”, has been fulfilled.