In philosophy, ideas are usually construed as mental representational images of some object. Ideas can also be abstract concepts that do not present as mental images.[Many philosophers have considered ideas to be a fundamental ontological category of being. The capacity to create and understand the meaning of ideas is considered to be an essential and defining feature of human beings. In a popular sense, an idea arises in a reflexive, spontaneous manner, even without thinking or serious reflection, for example, when we talk about the idea of a person or a place. A new or original idea can often lead to innovation.