Patrick Matthew wrote in his book On Naval Timber and Arboriculture (1831) of "continual balancing of life to circumstance. ... progeny of the same parents, under great differences of circumstance, might, in several generations, even become distinct species, incapable of co-reproduction."
Patrick Matthew escribiu no complicado libro On Naval Timber and Arboriculture (1831) sobre o "continuo eqilibrio da vida coas circunstancias. ... proxenie destes mesmos parentes, baixo grandes diferenzas nas circunstancias, podería, en varias xeracións, mesmo converterse en especies distintas, incapaces de correprodución."