Different activities often involve different materials, so that decisions that affect the materials in one activity do not interact with decisions that affect the materials of the other activity. Different activities often take place at different times, thus limiting the channels through which they might constrain one another. These times might be standardized points during the cycle of the day or week, or their ordering might be constrained by some kind of precondition that the first activity produces and successive ones depend upon. Simon pointed out that division of labor eases cognitive burdens. It does this in part by supplying individuals with separate spheres in which to conduct their respective activities.
Many activities have background conditions that are maintained without reference to specific goals.
For example, one maintains stocks of supplies in the pantry, puts things back where they belong, and so forth. What these practices stabilize are the relationships between an agent and the materials used in its customary activities. They tend to ensure, for example, that one will encounter one's hammer or the currently opened box of corn flakes in definite sorts of recurring situations. They thus reduce the complexity of life, and the variety of different hassles that arise, by encouraging the rise of routine patterns and cycles of activity rather than a constant stream of unique puzzles. Attributes of tools.