Inspiring a new generation

This is from Wikipedia:

"Calculus is the study of change, in the same way that geometry is the study of shape and algebra is the study of equations."

I don't remember the source but I liked this one:

"The importance of calculus is that most of the laws of science do not provide direct information about the values of variables which can be directly measured. This is why it's important to have a mathematical way of talking about change. That's why you see the concept of the derivative used throughout science"

EDIT:

The source is http://www.math.hawaii.edu/~lee/calculus/

He has written a paragraph about importance of calculus,you might get some idea from there,I hope. I enjoyed reading it.

This is a nice collection as well:

http://www.math.okstate.edu/~wli/teach/fmq.html

Personally, I liked this one attributed to Laplace:

It is interesting thus to follow the intellectual truths of analysis in the phenomena of nature. This correspondence, of which the system of the world will offer us numerous examples, makes one of the greatest charms attached to mathematical speculations.

I can you recommend the collection of quotes from Doron Zeilberger http://www.math.rutgers.edu/~zeilberg/quotes.html

(From The Unreasonable Effectiveness of Mathematics in the Natural Sciences)

"The miracle of the appropriateness of the language of mathematics for the formulation of the laws of physics is a wonderful gift which we neither understand nor deserve. We should be grateful for it and hope that it will remain valid in future research and that it will extend, for better or for worse, to our pleasure, even though perhaps also to our bafflement, to wide branches of learning."

An advice from Jean d'Alembert to those who questioned the calculus could be appropriate :-) :

$$``\text{Allez en avant, et la foi vous viendra.''}$$

$$\text{(Push on and faith will catch up with you)}$$

(from these quotations or the answer from Piero D'Ancona at MO in 'Describe a topic in one sentence')

Silvanus Thompson's 1914 book "Calculus Made Easy" (available here) starts with :
$$``\text{What one fool can do, another can.''}$$ $$\text{(Ancient bimian Proberb)}$$ (this was often cited by Richard Feynman)

Thompson added (page 13) :
"Considering how many fools can calculate, it is
surprising that it should be thought either a difficult
or a tedious task for any other fool to learn how to
master the same tricks."