Yes. He has spoken to me also. He said
'Differentiation is defined, loosely as follows: it is a techneque used when attempting to discover the absolute, faultless and exact gradient of a curve such as y=x^3. This curve will be used as an example throughout the rest of this explanation. Suppose that we wanted to find the exact vale of the gradient at the point x=2. If we wanted we could draw a strate line at a tangent to the curve at this point... however this would only give us a vague idea of the gradient. In order to find the gradient EXACTLY we must find a general equation for the gradient across the entire curve. The procedure needed to find this equation is simple. Simply take the power (3) and multiply it by the number before the x. Then lower the power by one. Therefore y=x^3 becomes dy/dx=3x^2. This works for any curve (with the exception of the exponential curve). It's simple i know. However the reasons behind this method's functioning is more complex and would requier the use of graph scetches etc to explain. Differentiation can come in very useful when attempting to discover the exact coordinates of a turning point of a curve. At a turning point, the gradient equalls zero so you simply equate dy/dx to zero. In this example therefore, solving the equation 0=3x^2 would give you the coordinates of the turning point (0,0). You can also find out what kind of turning point it is by either finding the gradient of the curve on either side of the turning point: if they are both posetive or both negative then it is a point of inflection; negative on he left and posetive on the right is a minimum turning point and posetive on the left and negative on the right is a maximum turning point. Alternetively you can double differentiate it (dy^2/d^2x) to discover the answere...'
then he started talking about integration. Now i'm fascinated by Maths.