  We introduce the ideal Gaussian glass-forming system as a model to describe
the thermodynamics and dynamics of supercooled liquids on a local scale in
terms of the properties of the potential energy landscape (PEL). The first
ingredient is the Gaussian distribution of inherent structures, the second a
specific relation between energy and mobility. This model is compatible with
general considerations as well as with several computer simulations on atomic
computer glass-formers. Important observables such as diffusion constants,
structural relaxation times and kinetic as well as thermodynamic fragilities
can be calculated analytically. In this way it becomes possible to identify a
relevant PEL parameter determining the kinetic fragility. Several experimental
observations can be reproduced. The remaining discrepancies to the experiment
can be qualitatively traced back to the difference between small and large
systems.
