I aim to put into effect a new method for discerning the properties of dark energy (DE) from observational data that will be collected by the Euclid satellite. Current methods are tuned for discovery of any effect of DE that is different from the cosmological constant. Unfortunately, they most likely will not be able to determine what the precise mechanism is. For this, we must measure the scale dependence of the effect of DE on the growth of structure in cosmology and relate this to the theoretical model space.All classes of DE models predict some average equation of state and some averaged growth rate for dark matter perturbations. The precise values of these parameters are determined by some combination and evolution history of the Lagrangian coefficients. However, different classes of DE models predict fundamentally different scale dependence in appropriate model-independent observables. This allows us to disambiguate the DE model class.I am one of the proponents of this new method of probing DE and a recognised expert on the theory and phenomenology of general DE models. Holding this Fellowship now would allow me to develop this method further, integrating it with the work of the Euclid collaboration, such that it could be in place in time for when Euclid starts taking data in 2020. This training I would obtain would build out my skillset from the very theoretical toward observations.This method is unique in that it would allow us to exclude any scalar-field model as a mechanism for DE. If DE is a scalar field, this method would place constraints or exclude whole classes of theories without involving potentially unphysical parameterisations.