The optimum population is, then, less than the maximum.

Of course, a positive growth rate might be taken as evidence that a population is below its optimum.

A finite world can support only a finite population; therefore, population growth must eventually equal zero.

The rational man finds that his share of the cost of the wastes he discharges into the commons is less than the cost of purifying his wastes before releasing them.

But as population became denser, the natural chemical and biological recycling processes became overloaded, calling for a redefinition of property rights.

However, I think the major opposition to ecology has deeper roots than mere economics; ecology threatens widely held values so fundamental that they must be called religious.