These aspects of the overall disease that have attacked humanity at the beginning stage of existence are parasites of an uncommon breed, so cruel and thoughtless as to be impossible to describe in human terms.
(the overall disease; have attacked; humanity; L:at the beginning stage of existence) (These aspects of the overall disease; are; parasites of an uncommon breed, so cruel and thoughtless)
the overall disease These aspects of the overall disease
have attacked are
humanity L:at the beginning stage of existence
parasites of an uncommon breed, so cruel and thoughtless