The are a couple of Gestalt principles at work here - the figure/ground relationship is what makes this difficult to discern at first because the illusion is perpetuated by the background actually being the figure. Upon this relationship, pragnanz is played out, reducing the complex lines in the relief of the limestone into a shape with which we are familiar, much like the FedEx logo. Continuity and closure is at work here as well.
To better understand the principles of Gestalt theory I am asking you to use class time today to visit either the Holland Building or the Eccles Fine Arts Center and discern these principles in their architectural design.
Remember, figure/ground relationships are the canvas upon which the other principles function; similarity, proximity, pragnanz, continuity, and closure. Observe both interior and exterior elements of your selected edifice, photograph them and upload your observations to your blog, calling this post Gestalt in Architecture.