 In December, 1909, Moore gave a paper at the Aristotelian Society in which he introduced the term “sense  data”.[13]  The paper again divided “mental acts” from their objects, and it observed that we are aware of a difference between mental act and non-mental object: when we perceive one color and then another, the act of consciousness is of the same type, whereas the two colors that are objects of the act differ. Such acts of consciousness can themselves differ in quality (one mental act may be a perceiving, another a willing, etc.), and many mental acts may be conjoined to form a complex mental entity. But such acts are distinct from their objects, even if those objects exist only when we perceive them, as, Moore reports, some people believe about colors. He then introduces the term “sense data”: