  Rapidly cooling a liquid may result in a glass transition, creating an
amorphous solid whose shear and bulk moduli are finite. Even when done with
constant density, these resulting moduli depend strongly on the rate of
cooling. Understanding this phenomenon calls for analyzing separately the "Born
term" that exists also in perfectly ordered materials and the contributions of
the "excess modes" that result from glassy disorder. We show that the Born term
is very insensitive to the cooling rate, and all the variation in the shear
modulus is due to the excess modes. We argue that this approach provides a
quantitative understanding of the cooling rate dependence of a basic linear
response coefficient, i.e. the shear modulus.
