Should we follow nature?

Stoic morality is universalist: there is a natural law, the expression of the single logos, binding on all rational beings everywhere. Good and evil depend neither on convention nor on cities: to live according to nature is to live according to this reason common to all humankind.

Cicero, On the Republic, book III · Marcus Aurelius, Meditations, IV, 4

In "Nature", Mill rejects the idea that the natural order supplies a moral standard: useful action consists precisely in correcting its spontaneous course, and nature daily commits what we would punish in human beings. Yet he does not make productive transformation an end without limits: cultivating every piece of land capable of growing food, ploughing up every flowery waste or natural pasture, and exterminating non-domesticated birds and quadrupeds as rivals for food would sacrifice the beauty and solitude that human flourishing needs. His defence of the "stationary state" thus combines the improvement of nature with the preservation of wild places, without positing moral equality among all forms of life.

Three Essays on Religion, "Nature" (posthumous, 1874) · Principles of Political Economy, IV, ch. 6, §2

The principle of utility serves as a universal criterion of the good, the same for all men and all ages: Mill does not relativise morality to cultures. The good is an objective fact, happiness, measurable by its effects, which ranks him on the side of a naturalistic universalism rather than relativism.

Utilitarianism, ch. 2 and 4 (the greatest happiness principle as a universal criterion)