It embodies the reproductive instinct, but restrains and guides it in view of ultimate consequences.
So much for the views and teaching of Malthus.

To him no ethical standard was violated in preventing offspring by protracted continence, or lifelong celibacy, provided the motive was the inability so to provide for a family as to require no aid from the state.

And it is difficult to escape this conclusion.

There is no ethical, Christian, or social law, that directs a man or woman to procreate their kind if they cannot, or have reasonable grounds to think they cannot, support their offspring without aid from others.
There can be, therefore, no just law that decrees that men or women shall marry under such circumstances.

In fact most philanthropists think they violate a social and ethical law if they do marry.
But, if with Paul, they resolve that it is better to marry than to burn, is there any law that can or should prevent them selecting the occasions of their union, with a view to limiting fertility.
Abstention is the voluntary hindrance of a desire, when that desire is strongest in both sexes; and as such it limits happiness, and is in consequence an evil _per se_.