Copernicus makes the sun _to be motionless_, and the scientific world bows before his authority. Then we have the recurrent curves, _closed orbits_ (or ellipses) with their axes and their _invariable plains_; for the planets _move round the centre of the fixed sun_. Whilst however learned men were striving with feverish ardour to confirm the system of Copernicus; whilst they were endeavouring to demonstrate in every possible way and by various means clearly, _that the sun is immoveable_: there came the discovery _that the sun moves_. The astronomers of the past century proved that the sun not only has the apparent motion, which every one sees; but that it also has a motion proper to itself. Herschel commenced defining the course and direction of it, and now-a-days no one doubts the truth of this fact, it being the general opinion that not only the sun moves itself, but that nothing at all in the world is in a state of rest. Astronomers, however, are of opinion that this discovery is of _no consequence whatever as regards the system of Copernicus, which is still considered by them to be the most correct of all and the only possible one_. For more than a century there has not been found a single astronomer or scientific man, to whom it has occurred _that the motion proper to the sun, might have, in some way or another, an influence on the present state of theoretical science_. They all seem to regard _this fact_ as an accident, involving no consequences and quite incapable of distracting them from their labours, which they continue to work in the same manner as is indicated in the system of Copernicus. If an advancing motion is admitted to be the motion proper to the sun, _the orbits traversed by the planets cannot be closed_. But the question may be asked: is it true that science contradicts itself in this way? We reply: Yes! astronomical _observation has overtaken theoretical or explicative science_. _Theory has stood still._ In order to set their minds at rest, learned men explain what they wish to explain, and just as heavenly phenomena were accounted for according the systems of Ptolemæus, of Copernicus and of Tycho de Brahe, so too there will be no lack of good reasons to account for the motion proper to the sun; only history will tell us that the astronomers of the last but one decennium of the XIX^{th} century have taught by writing and speaking in their schools, that the sun is at the same time moving and not moving. A science which cannot make any use of this immense discovery, nor deduce any application from it, does not possess any vital power; it is a dead science, it is strangled by those whose duty is to keep it alive, to lead it onwards to perfection. Astronomers assert "_that the sun conducts its system with himself in mundane space_," but in the same breath they add: "_with reference however to the planets it may be regarded as in a state of rest_." Hence astronomers have discovered _a motion which is at rest_.