By “species cowardice” we understand a constellation whereby, on the one hand, there exists a certain insight into what is morally ruinous in the perpetuation of the human species but, on the other hand, we see a certain avoidance of this insight and a refusal to accept its consequences. Cazalis describes this phenomenon when he writes that humanity ought really to be ashamed of itself (>Species Shame) but Man remains enslaved to the comparatively trivial experience of procreation:
“One cannot stress often enough how old this world already is. Contemporary Man has been seized by such a profound ennui and despises his own species to such a degree that he would surely take no steps to ensure its continuation, had Nature (…) not seen to it that procreation is associated with certain pleasures, the temptation of which – one should not hesitate to admit it – human beings can only rarely withstand for very long. Sometimes, however, one observes how Man rages and revolts against himself, full of shame at being so fatally similar similar to other animals and a ridiculous slave of Nature’s moods.” Cazalis leaves out of account here that potential separation of sexuality and procreation that was both preached and practiced by the Cathars and which is vouched for also by the Bible.
Maeterlinck too makes reference to this “species cowardice” diagnosed by Cazalis when he writes:
“If Man possessed a less intimidated understanding, humanity would long since have ceased to exist. Because then it would probably not have accepted life in the form in which it is imposed on us.” (Maurice Maeterlinck. Found by: Guido Kohlbecher)
We might develop Maeterlinck’s thought and say that a humanity less intimidated by the heritage of Nature and by cultural tradition would long since have carried through a Cultural Revolution involving our freeing ourselves, once and for all from that illusion of the ”naturalness” of all procreation and would have died out, instead of heeding, with cowardice and complacency, the “call of Nature” and imitating this latter, falsely taken as a model.
 „On ne dira jamais assez comme ce monde est vieux. L’homme s’ennuie si profondément aujourd’hui, et méprise si bien son espèce, qu’il ne ferait rien sans doute pour la perpétuer davantage, si la Nature (…) n’avait eu l’esprit d’attacher à la reproduction certaines voluptés auxquelles, il le faut bien avouer, l’homme a rarement la force de résister longtemps. – Mais parfois alors on le voit s’irriter, se révolter contre soi-même, honteux d’être aussi fatalement bestial, aussi ridiculement l’esclave du caprice de la Nature.“ (Henri Cazalis, Le Livre du neánt. Pensées douloureuses et bouffonnes, siehe https://fr.wikisource.org/wiki/Page:Cazalis_-_Le_Livre_du_n%C3%A9ant,_1872.djvu/60)