  In any domain involving some stressed solids, that is, from seismology to
general engineering, the strength of matter is a paramount feature to
understand. We here discuss the ability of a simple thermally activated
sub-critical model, that includes the auto-induced thermal evolution of cracks
tips, to predict the catastrophic failure of a vast range of materials. It is
in particular shown that the intrinsic surface energy barrier, for breaking the
atomic bonds of many solids, can be easily deduced from the slow creeping
dynamics of a crack. This intrinsic barrier is however higher than the
macroscopic load threshold at which brittle matter brutally fails, possibly as
a result of thermal activation and of a thermal weakening mechanism. We propose
a novel method to compute the macroscopic critical energy release rate of
rupture, G_a, solely from monitoring slow creep, and show that this reproduces
the experimental values within 50% accuracy over twenty different materials,
and over more than four decades of fracture energy.
