From Descartes to the First Law of Thermodynamics

“A cause must be at least as great as its effect.”
Renee Descartes

Because otherwise some of the effect would not be accounted for.

But… An effect must be at least as great as its cause. Otherwise some of the cause would simply “disappear”. It could never be perceived.

Therefore, cause and effect are necessarily equal and constitute a conserved quantity.

Cause and effect are the philosophical terms for energy.

Energy is the scientific term for cause and effect.