What is Calculus? Why and how should we enjoy, understand or play with it?

Calculus plays a pivotal role in our life? In fact it is essential fir survival? Life is synonymous with change? And is the only constant in life? What change is taking place is something we are all interested? Fir example is the poverty level in the society increasing? Is the crime rate in the society correlated with poverty? Her I have talked about the crime rate? So change and then rate of change is some thing which is the essence of calculus?