Contrary to the initial comment on this page, the director Luis Bunuel did not use two different actresses to play the lead role as a plot device to show "One actress for her placid nature and another actress for her tempermental side."
While this is an oft-repeated misconception, it's not remotely true. In Luis Bunuel's autobiography, "My Last Sigh" (A fantastic book, still in print) the director discusses the reason for this unique directorial device, and how funny he finds it that so many "fans" assume that the choices were based on the actresses temperment or his desire to "express" something obscure. In truth, two actresses were used simply because the lead actress quit partway through production after having completed many critical scenes. Luis was beside himself over the wasted time and money in reshooting, so he hired a replacement to shoot only the missing scenes, and edited them irregardless of who was acting in a given scene. It served him well, as the end result was brilliant.
While this is an oft-repeated misconception, it's not remotely true. In Luis Bunuel's autobiography, "My Last Sigh" (A fantastic book, still in print) the director discusses the reason for this unique directorial device, and how funny he finds it that so many "fans" assume that the choices were based on the actresses temperment or his desire to "express" something obscure. In truth, two actresses were used simply because the lead actress quit partway through production after having completed many critical scenes. Luis was beside himself over the wasted time and money in reshooting, so he hired a replacement to shoot only the missing scenes, and edited them irregardless of who was acting in a given scene. It served him well, as the end result was brilliant.