Of fundamental importance in almost all sciences is the concept of "event". The first object of this elementary study is to provide by a careful selection of materials an appropriate mathematical frame for this concept which specially includes the laws which the "watches", another important concept used frequently in this research, record the events. Armed, then, with this mathematics, the Gravitational Clouds Theory, a somewhat strange theory of gravitation concerning the role of the matter and energy in the universe, is proposed. This theory leads to miscellanies results some of which are: the second Einstein's postulate; the well known identity E = mc2; the time-dilation phenomenon and Fitzgerald-Lorentz contraction. This theory will also explain why we never feel the speed of our planet, what is the origin of dark matter and many other extraordinary results associated with cosmology. It is believed that this kind of verification may even lead to the celebrated "every thing" theory. We hope the readers will find something of interest in this book.