[112] M: p. 93. [113] M: pp. 92, 93. [114] M: p. 93. [115] M: p. 94. [116] M: p. 94. By means of the properties of such a fluid, Gilbert could explain the unordered coming-together that he called coacervation.[117] Different bodies have different effluvia, and so one has coacervation of different materials. Thus, in Gilbert's philosophy air was the earth's effluvium and was responsible for the unordered motion of objects towards the earth.[118] [117] M: p. 97. [118] M: p. 92 (see also p. 339). Although Gilbert does not make it explicit, this would solve the medieval problem of gravitation without resorting to a Ptolemaic universe. In addition, since coacervation is electric, and electric forces can be screened, it should have been possible to reduce the downward motion of a body by screening! The analogy between electric attraction and fluids is a most concrete one, yet lying beneath this image is a hypothesis that is difficult to fix into a mechanical system based upon contact forces. This is the assumption that under the proper conditions bodies tend to move together in order to participate in a more complete unity.[119] The steps in electrical attraction were described as occurring on two different levels of abstraction: first one has physical contact through an effluvium or "spiritus" that connects the two objects physically. Then, as a result of this contact, the objects somehow sense[120] that a more intimate harmony is possible, and move accordingly. Gilbert called the motion that followed contact, attraction. However, this motion did not connote what we would call a force:[121] it did not correspond directly to a push or pull, but it followed from what one might term the apprehension of the possibility of a more complete participation in a formal unity. The physical unity due to the "spiritus" was the prelude to a formal organic unity, so that _humor_ is "rerum omnium unitore." Gilbert's position can be best seen in the following:[122]