If the sun is _not fixed_, the system of Copernicus falls to ground. Either the sun moves, or does not; a moving sun in a condition of rest, _is an impossibility_. If the sun moves, there is _no fixed centre_, there are _no closed or recurrent curves and no plains of orbits_. If these must be obtained at any price, the sun must be definitively fixed, it cannot be permitted _to move onwards and yet at the same time not to move_. The fact that the sun moves, cannot now be altered and cannot be any longer ignored; and if mathematicians and astronomers do notwithstanding assert, that the sun may with reference to its own planetary system be regarded as fixed, or in a condition of rest, in that the system moves as a whole without any change taking place in the relative position of the planets to each other, or in their relation to the sun; in fact without any alteration taking place in the _configuration_ of the system--we reply, this is one of those meaningless phrases, which should find no place in a scientific discussion. _A body which is in motion cannot be in any way regarded as being motionless_, it would be just as reasonable to say that a locomotive, dragging a train of carriages full of passengers, could with reference to the latter be regarded as motionless. The actual meaning of such an assertion is that the planets are attached to the sun in such a manner, that they can neither approach to, nor recede from it, but must follow it whithersoever it goes. We may in thought pursue a train of hypotheses and suppositions, but they do not thereby acquire reality; still, in a normal condition of the human intellect, it is impossible to conceive that any thing can exist and not exist at the same time. From this confusion of ideas, it might seem as if theoretical astronomy had got into an untenable position which is irreconcilable with science and ought therefore to endeavour to enter upon a better state, as soon as possible. _Theory ought therefore, either to have accepted as a fact, the motion proper to the sun with all its inevitable consequences, or else, to have denied this motion altogether._ But the astronomers ignore this alternative, they have decided, once for all and irrevocably _that the sun moves and that at the same time it shall be motionless_. In this manner science loses its reputation and all learnedly technical expressions and formulas are not sufficient to cover the weak part. _The sun cannot be rendered motionless_, and if astronomers and men of science of the present day continue to ignore this fact, they need not be surprised at the inevitable consequences of their own acts.