Abstract ideas do not form a fourth class of ideas but are fractions of particular, general, or imaginary ideas, and may (as Berkeley, reporting the metaphysical doctrine, says) be single or partial properties mentally detached from the collective properties forming an object. In this case they are abstracted properties, not ideas. Since general ideas are less complete than the particular ideas from which they were drawn, they are abstract ideas in so far as they are partial ideas; but all abstract ideas are not general ideas. Berkeley's nominalism is based on the supposed impossibility of forming any sort of partial idea, and he now proceeds to reproduce the metaphysical account of the general abstract idea. 'And as the mind frames to itself abstract ideas of qualities or modes, so does it, by the same precision or mental separation, attain abstract ideas [general ideas] of the more compounded beings which include several co-existent qualities. For example, the mind having observed that Peter, James, and John resemble each other in certain common agreements of shape and other qualities, leaves out of the complex or compounded idea it has of Peter, James, and any other particular man, that which is peculiar to each, retaining only what is common to all, and so makes an abstract [general] idea wherein all the particulars equally partake--abstracting entirely from and cutting off those circumstances and differences which might determine it to any particular existence. And after this manner it is said we come by the abstract [general] idea of man, or, if you please, humanity or human nature; wherein it is true there is included colour, because there is no man but has some colour, but then it can be neither white, nor black, nor any particular colour, because there is no one particular colour wherein all men partake. So likewise there is included stature, but then it is neither tall stature, nor low stature, nor yet middle stature, but something abstracted from all these. And so of the rest. Moreover, there being a great variety of other creatures that partake of some parts, but not all, of the complex idea of man, the mind, leaving out those parts which are peculiar to men, and retaining those only which are common to all the living creatures, frames the idea of _animal_, which abstracts not only from all particular men, but also all birds, beasts, fishes and insects. The constituent parts of the abstract idea of animal are body, life, sense, and spontaneous motion. By _body_ is meant body without any particular shape or figure, there being no one shape or figure common to all animals, without covering either of hair, or feathers, or scales, &c., nor yet naked: hair, feathers, scales, and nakedness being the distinguishing properties of particular animals, and for that reason left out