One view on the nature of ideas is that there exist some ideas (called innate ideas) which are so general and abstract, that they could not have arisen as a representation of any object of our perception, but rather were, in some sense, always in the mind before we could learn them. These are distinguished from adventitious ideas which are images or concepts which are accompanied by the judgment that they are caused by some object outside of the mind.
Another view holds that we only discover ideas in the same way that we discover the real world, from personal experiences. The view that humans acquire all or almost all their behavioral traits from nurture (life experiences) is known as tabula rasa ("blank slate"). Most of the confusions in the way of ideas arise at least in part from the use of the term "idea" to cover both the representation percept and the object of conceptual thought. This can be illustrated in terms of the doctrines of innate ideas, "concrete ideas versus abstract ideas", as well as "simple ideas versus complex ideas".
Plato was one of the earliest philosophers to provide a detailed discussion of ideas. He considered the concept of idea in the realm of metaphysics and its implications for epistemology. He asserted that there is a realm of Forms or Ideas, which exist independently of anyone who may have thought of these ideas. Material things are then imperfect and transient reflections or instantiations of the perfect and unchanging ideas. From this it follows that these Ideas are the principal reality (see also idealism). In contrast to the individual objects of sense experience, which undergo constant change and flux, Plato held that ideas are perfect, eternal, and immutable. Consequently, Plato considered that knowledge of material things is not really knowledge; real knowledge can only be had of unchanging ideas.