Philosophical Idealism is a theory that suggests reality is fundamentally mental or immaterial. According to this view, the material world is either dependent on the mind or is an extension of it. Idealists argue that our perceptions and thoughts shape our understanding of reality, emphasizing the importance of ideas over physical objects. One of the key figures in this philosophy is George Berkeley, who famously stated, "To be is to be perceived." This means that objects only exist as long as they are observed. Idealism contrasts with Materialism, which posits that only physical matter is real and that consciousness arises from material interactions.