This estimate of gravity, as an abstract quality or property, might be repeated of all other physical properties, as well as of those abstract conceptions which are moral and intellectual. Goodness came to be considered as a type, varying indeed in different peoples, according to their race, and their local, moral, and civil conditions, but as a type which corresponded to the mutual relations of men, and to their superstitions and religious beliefs as to the nature of things. In this case also the abstract conception of the good, the fitting, the useful, which constantly recur in popular speech are regarded, not as mythical powers personified in a human form, but as having a real existence in nature, as something extrinsic to the person or thing in which they are manifested, and as acting upon them as a living and causative power. The same may be said of all other abstract conceptions. Hence, in addition to the formation of cosmic, moral, and intellectual myths, fashioned after the pattern of humanity, logical conceptions arose in the mind, necessary for the exercise of human speech and for a man's converse with himself, and these were regarded as having a real existence, manifested in things and persons and in the system of nature. These entities have their origin in the same faculty as the others; in every conception presented to the mind and reproducing the primitive sensation or emotion, the external or internal phenomenon implicitly generates the subject, and with this the cause. These abstract conceptions did not and do not result in the anthropomorphism of phenomena or ideas, but are transformed into entities which have a real existence. We must also observe the mobility and interchangeableness of these fetishes, myths, and imaginary entities in the primitive times of the human race, and even in later ages; at one time the fetish acts as a myth, at another the myth has a logical existence. Of this there are many proofs in the traditions of ancient peoples, in the intellectual life of modern savages, and in that of the civilized nations to which we ourselves belong. The historic development does not always follow the regular course we have just described, although these are, in a strictly logical sense, the necessary stages of intellectual evolution. Historically they are often jostled and confounded together by the lively susceptibility and alacrity of the imagination of primitive man, and it is precisely this characteristic which makes these marvellous ages so fertile in fanciful creations, and also in scientific intuitions.