It's also the mother of invention.
In my opinion, it's simple. A necessity is something that urges people to find a way to suffice their needs to live a more comfortable life. It's a well know fact that everything we need is not provided by nature thus, we find ways to satiate our needs by inventing. Necessity is why we have the things that we have now and why life presently is easier than life in the old days. The necessity of keeping track of records is what led to writing and the necessity of communicating with one another is what led to the development of language. The way I see it, necessity, invention's mother, is what's going to lead the further progress of humanity.