This proverb just means that there is nothing like a pressing and urgent need for setting people to work to find a way of meeting it. If we could get all we want from nature we should not bother to invent anything; as we can’t, we are forced to find out ways and means to satisfy our needs.
In the early days of mankind, the necessity of communicating with one another led men to the invention of languages. Later, the necessity of keeping some record of what they did or said led to the invention of writing. Later still, the necessity of spreading news and knowledge led to the invention of printing.
These are only few illustrations to prove that from the very beginning of human life that man has been making inventions and discoveries out of sheer necessity. Hence we recognise “necessity” for the progress of the human race.