  We consider the phenomenology of cosmic-rays (CRs) and stress the interest of
jointly studying their properties over the whole energy spectrum. While UHECRs
are known to raise important physical and astrophysical problems, we recall
that low-energy CRs also remain poorly understood, and we indicate the possibly
important role of superbubbles in accelerating CRs up to a few EeV. We also
investigate the viability of holistic models, and show that a unique type of
sources producing CRs with a spectrum in E^{-2.3} could in principle account
for all the CRs in the universe.
