Hello there!
This example is meant to illustrate an imperfect duty.
Explanation:
Immanuel Kant developed what we know as the Kantian theory. This was developed a product of enlightment-rationalism. In this theory, he distinguished perfect and imperfect duties. So, the imperfect duties -according to Kant- can be flexible and be applied at a certain period of time and in particular spaces.
And as the example says, not all the men despairs after a series of troubles. It is flexible and that is why it is an imperfect duty.