"Merino sheep always flock while Highland sheep spread. The reason is that in Spain the summer feeding and winter feeding of the sheep were widely separated, and the shepherd had to march them many miles along the road and through the villages. If they did not flock, they would soon be lost in their seasonal journey. On the other hand, the Scottish shepherd never moves his Highland sheep large distances and wishes them to spread out as much as possible over the hills so that no one area is overgrazed, and both of these characteristics have been achieved by selective breeding."

“RULE 5 The abundance of organisms in nature varies with their size.”

“First, there was a selection for an increase in size by becoming multicellular, and once achieved there was a selection for better integration, a better coordination of the adhering cells to compete effectively for energy and for a way to reproduce successfully. Then, which each successive step of size increase, propelled always by the fact the uppermost size niche is never filled, there has been a further selection pressure for integration and coordination, often by new and innovative devices to accommodate the newly created larger organism.”

“RULE 2 Surfaces that permit diffusion of oxygen, of food, of heat in and out of the body, vary with size.”

“RULE 4 The rate of various living processes varies with size, such as metabolism, generation time, longevity, and the speed of locomotion.”

“RULE 3 The division of labor varies with size.”

“RULE 1 Strength varies with size.”