Art is that which is made with the intention of stimulating the human senses as well as the human mind and/or spirit. There is no general agreed-upon definition of art, since defining the boundaries of "art" is subjective, but the impetus for art is often called human creativity. An artwork is normally assessed in quality by the amount of stimulation it brings about. The impact it has on people, the number of people that can relate to it, the degree of their appreciation, and the effect or influence it has or has had in the past, all accumulate to the 'degree of art.' Most artworks that are widely considered to be "masterpieces" possess these attributes. Something is not generally considered 'art' when it stimulates only the senses, or only the mind, or when it has a different primary purpose than doing so. However, some contemporary art challenges this idea.