Problem with evils

"The principle according to which population increases prevents the vices of mankind or the accidents of nature, the partial evils arising from general laws, from obstructing the high purpose of the creation." p. 116, XVIII

"The idea that the impressions and excitements of this world are the instruments in which the Supreme Being forms matter into mind, and that the necessity of constant exertion to avoid evil and to pursue good is the principal spring of these impressions and excitements, seems to smooth many of the difficulties that occur in a contemplation of human life, and appears to me to give a satisfactory reason for the existence of natural and moral evil, and, consequently, for that part of both, and it certainly is not a very small part, which arises from the principle of population." p.124, last paragraph of XIX

Reading this text I picked out three major themes:

improvement/perfectibility of society

role of the principle of population increase in the improvement of society

evils from the general laws of nature/evils that arise from the principle of population and the place of these evils in the divine plan of the Supreme Being and in the improvement of society

The passages I quoted above seem to draw links between all three of these themes.  Can we unpack the above statements (and perhaps use other ones as well) to delineate the links between the three themes?  In the first quote Malthus says how the principle of population checks the vices of men and of nature from obstructing God's divine plan, and in the second quote he writes that natural and moral evil arise from the principle of population but are justified in light of what exactly?  I'm having trouble seeing how these two quotes are not contradictory.