A representation or formulation produced by the mind. Everything, in the world and Heaven, is an idea. Ideas may be true or false, wrong-minded, right-minded or one-minded. 1. The ego is composed of mad ideas, false ideas. The ego itself is merely an idea, not a fact (see T-4.II.2:6), which is why we can be free of it. 2. All physical forms, including the body, are produced by ideas, being merely the outward reflection of ideas. 3. Unlike physical forms, however, ideas can truly be shared (see T-5.I.1-2). Instead of dividing them, sharing ideas reinforces and increases them (see giving/receiving). The sharing of ideas is how minds can unite. 4. The title phrase of each Workbook lesson is referred to as an idea (as "the idea" or "today's idea" or "the idea for the day"). 5. Heaven itself is composed of ideas. The Holy Spirit, eternity, love, joy and we ourselves are all ideas, and thus can be infinitely shared. Heavenly ideas are far beyond the tiny, changing notions we call ideas. They are not subjective pictures of reality, but are reality itself (see Thoughts of God). Even God is an idea (see T-15.VI.4), though He is not an idea conceived by some other mind. The word "concept" in the Course is very similar to the word "idea," though, unlike ideas, concepts stop short of Heaven. For the word "concept" emphasizes our making, our conceiving. Thus, concepts are generally of the ego, and though they can reflect reality, they must be finally transcended in order to once again know the limitless ideas of Heaven. See "ideas leave not their source"