McGilligan, Patrick. . Alfred Hitchcock : a life in darkness and light / Patrick McGilligan. 1st ed. 006039322X series New York : Regan Books, c2003.
Call#: Van Pelt Library PN1998.3.H58 M38 2003

    In Part 5 (Paramount: The Glory Years) chapter 15, the author describes the process by which Hitchcock decided on the actors that he chose to star in the film. Originally, James Stewart had be slated for the role of Thornhill, but due to the poor performance of Vertigo in the box office it was unclear whether Hitchcock and the studio could justifiably use him instead of Cary Grant. Stewart was an immensely popular actor, but not considered sexy enough for the role. By using Grant who appeared younger, the studios were happy because there would be a greater draw for women to see the film and Hitchcock was happy because he signed a lead actor whom the audience would have more emotion invested in. Hitchcock next arrived at the task of picking the female lead. He rejected the studio's suggestions and chose Eva Marie Saint, a well regarded actress but not regarded as exceptionally sexy or mysterious. Hitchcock hoped to mold her and give her a specific role. James Mason comments on this, accusing Hitchcock of using his actors as "animated props".

    The choice of actors in a film a critical first step towards creating the desired output. Despite Hitchcock's often firm hand in micromanaging the details of each shot, the actor has a great deal of responsibility and artistic license in the way they portray their character in the film. Hitchcock made his decisions based on the overall effect upon the audience. Thus, careful selection of each actor was an important prerequisite for achieving his desired outcome in each shot. The decisions made however led to great success. The strength of the movie rests on the audience's concern for Thornhill's successful resolution of the dangerous challenge he was forced into, and also of Eve's safety as she plays the role of secret agent to the enemy spy. While casting the correct actor into a role is critically important, it can also be argued that massaging that actor into the desired character during filming is of equal importance. If the character is not playing the part as envisioned, the director essentially loses control over his tool he uses to manipulate the emotions of the audience.  Hitchcock not only carefully screened his actors, but was also known for his adept manipulation of their skills into the finished product he himself desired.