This is a book review of LONG_The Cosmic Revolutionary's Handbook by Luke Barnes. It is a popular account of modern cosmology, with more emphasis than most similar books on two important aspects: how conclusions are arrived at and which conclusions depend on which observations. Both of those are intended as a challenge to would-be cosmic revolutionaries, i.e. those who would like to replace the current standard model of cosmology with some other theory. After the first chapter describing how science works, the next seven cover standard topics: the darkness of the night sky, redshifts of galaxies, cosmological time dilation and surface-brightness reduction (two conseqences of the cosmological redshift which are difficult to explain via other means), the cosmic microwave background, the Lyman-α forest, cosmic elemental abundances, and inflation. Chapter 9 looks at some alternative cosmological theories (some familiar, others less so) and the final chapter deals with ``some loose ends, untested predictions, observational puzzles, and missing pieces'' such as dark matter, dark energy, satellite galaxies, the lithium problem, primordial neutrinos, matter-antimatter asymmetry, primordial gravitational waves, and the birth of the Universe. The book is well written and and includes a bit more `how' (do we know) in addition to the `what' of the standard model of cosmology. The book is a breezy but careful introduction to where we are in our understanding of the Universe and how we got there.