Thomas Robert Malthus said this quote

It may be said with truth that man is always susceptible ofimprovement

~ Thomas Robert Malthus

The vices and moral weakness of man are not invincible: Man is perfectible, or in other words, susceptible of perpetual improvement.

~ Thomas Robert Malthus

as long as agreat number of those impressions which form character, like the nicemotions of the arm, remain absolutely independent of the will of man,though it would be the height of folly and presumption to attempt tocalculate the relative proportions of virtue and vice at the future periodsof the world, it may be safely asserted that the vices and moralweakness of mankind, taken in the mass, are invincible.

~ Thomas Robert Malthus

I should be inclined, therefore, as I have hinted before, to consider the world and this life as the mighty process of God, not for the trial, but for the creation and formation of mind, a process necessary to awaken inert, chaotic matter into spirit, to sublimate the dust of the earth into soul, to elicit an ethereal spark from the clod of clay. And in this view of the subject, the various impressions and excitements which man receives through life may be considered as the forming hand of his Creator, acting by general laws, and awakening his sluggish existence, by the animating touches of the Divinity, into a capacity of superior enjoyment. The original sin of man is the torpor and corruption of the chaotic matter in which he may be said to be born.

~ Thomas Robert Malthus