There may, for aught we know, be good reasons why Providence interposes not in this manner; but they are unknown to us; and though the mere supposition, that such reasons exist, may be sufficient to save the conclusion concerning the Divine attributes, yet surely it can never be sufficient to establish that conclusion.
If every thing in the universe be conducted by general laws, and if animals be rendered susceptible of pain, it scarcely seems possible but some ill must arise in the various shocks of matter, and the various concurrence and opposition of general laws; but this ill would be very rare, were it not for the third circumstance, which I proposed to mention, viz.

the great frugality with which all powers and faculties are distributed to every particular being.

So well adjusted are the organs and capacities of all animals, and so well fitted to their preservation, that, as far as history or tradition reaches, there appears not to be any single species which has yet been extinguished in the universe.

Every animal has the requisite endowments; but these endowments are bestowed with so scrupulous an economy, that any considerable diminution must entirely destroy the creature.

Wherever one power is increased, there is a proportional abatement in the others.