The fact of the matter is that we live in an orderly universe, but we are

not orderly ourselves. We are not in correspondence with our true

environment. Our true environment is an orderly and perfect universe.

The hidden law of life is love or co-operation. Rheinheimer the biologist

teaches that all through nature, in both plant and animal, health and

progress follow when this law of co-operation is obeyed, and that

disease and disorder follow its violation. That is, when predatory or

parasitic practices are followed, instead of those of service and cooperation.

I can't figure out what that part of the sentence says?

Maybe: That everything in plants, animals, health and progress happen naturally when this law of cooperation is obeyed and diseases and disorder take place when this natural law is violated?
Right. You figured it out.
OK. Thanks.