Objective: This study investigates the application of aesthetic principles to designed objects with which we interact, specifically looking at the impact of perceived function of the objects on perceptions of visual appeal. Background: Previous studies have demonstrated that a product’s judged beauty or visual appeal is related to perceptions of its usability. Arguments have been put forward for both directions of causality leading to “what is beautiful is usable” and “what is usable is beautiful” hypotheses. Explanations for the relationship between usability and beauty judgments include stereotype effects, ecological explanations, and cognitive processing viewpoints. The current studies contribute to this debate by manipulating usability and aesthetic principles independently to determine whether well-established aesthetic principles are contingent on perceived function. Method: 248 participants were recruited for two experiments. In Experiment 1, participants viewed sixteen illustrations that varied in ways that frequently increase the beauty of objects (i.e., basic principles such as symmetry, balanced massing, curvature, and prototypicality) and rated their degree of visual appeal. In Experiment 2, participants rated the appeal of the same stimuli as in Experiment 1 but were primed by instructions describing the illustrations as either alternative designs for microwave control panels or designs of building façades. Results: Strong support for the aesthetic principles of symmetry and spatial massing, but not curvature, were found in both experiments. Participants generally preferred stimuli that were symmetrical and evenly massed (i.e., "balanced"). Additionally, the manipulation of a functional prime significantly interacted with several aesthetic principles that relate to the match between the supplied prime and the prototypicality of the stimulus for the primed class of objects. Conclusions: Aesthetic principles of symmetry and spatial massing can be considered very potent ways to influence a user’s degree of perceived visual appeal that are resistant to specific use cases or situations. Other principles, such as curvature preferences, seem to be limited by the prototypicality of curvature for a primed class of objects. So when considering whether “what is beautiful is usable” or “what is usable is beautiful," the results from the current study demonstrate that it may be more appropriate to say "what is familiar is beautiful."