He had wondered, as had most people at one time or another, precisely why an android bounced helplessly about when confronted by an empathy-measuring test. Empathy, evidently, existed only within the human community, whereas intelligence to some degree could be found throughout every phylum and order including the arachnida. For one thing, the empathic faculty probably required an unimpaired group instinct; a solitary organism, such as a spider, would have no use for it; in fact it would tend to abort a spider's ability to survive. It would make him conscious of the desire to live on the part of his prey. Hence all predators, even highly developed mammals such as cats, would starve. Empathy, he once had decided, must be limited to herbivores or anyhow omnivores who could depart from a meat diet. Because, ultimately, the empathic gift blurred the boundaries between hunter and victim, between the successful and the defeated. As in the fusion with Mercer, everyone ascended together or, when the cycle had come to an end, fell together into the trough of the tomb world. Oddly, it resembled a sort of biological insurance, but double-edged. As long as some creature experienced joy, then the condition for all other creatures included a fragment of joy. However, if any living being suffered, then for all the rest the shadow could not be entirely cast off. A herd animal such as man would acquire a higher survival factor through this; an owl or a cobra would be destroyed. Evidently the humanoid robot constituted a solitary predator.