  We present a systematic method to derive an ordinary differential equation
for any Feynman integral, where the differentiation is with respect to an
external variable. The resulting differential equation is of Fuchsian type. The
method can be used within fixed integer space-time dimensions as well as within
dimensional regularisation. We show that finding the differential equation is
equivalent to solving a linear system of equations. We observe interesting
factorisation properties of the D-dimensional Picard-Fuchs operator when D is
specialised to integer dimensions.
