Causal agent and Life principle

Causal agent noun - Any entity that produces an effect or is responsible for events or results.

Life principle and causal agent are semantically related. In some cases you can replace phrase "Life principle" with "Causal agent", this phrases are similar.

Life principle noun - A hypothetical force to which the functions and qualities peculiar to living things are sometimes ascribed.

Causal agent and life principle are semantically related. Sometimes you can use "Causal agent" instead a noun phrase "Life principle".