For Galen, the purpose of the divine Craftsman is, certainly, the most important cause, but the material cause must also be mentioned in a full account: matter represents the building-blocks used to realize the design, and in a sense provides a limitation to it. This interaction between design and material—and the assertion of the final cause in opposition to those who deny it—are the central features of Galen’s account. In the (strikingly anthropomorphic) account of the Craftsman’s construction of the human body at UP VI.13, however, Galen does indeed incorporate the five causes listed above. The Craftsman constructs the organs of the body as they are “because it is better so”, thus also bringing about the best possible “form”: this covers both final and formal causes. We must then see how he employs both “instruments” and “matter” to do so: this will take account of both instrumental and material causes, and although the distinction between these too may seem somewhat fluid, it it is further clarified that we should understand the wet and the dry as providing the material cause, while the hot and the cold are the “active instruments” which the Craftsman uses to shape these. This corresponds to the Aristotelian distinction between the active and the passive pair amongst the fundamental elements (see below, §6.1). In summarizing the five causes at the end of this passage, Galen uses the phrase “from the Craftsman” instead of “efficient”.