According to the most probable cosmogonic theory, Mars is older than our planet by several million years and much more advanced along its path of destiny than ours. The inhabitants of Mars may have been signalling to us for 100 thousand years. Nobody on our planet would have suspected it. It is only since the seventeenth century that astronomers may have thought, not of discovering such signals, for their instruments were not sufficiently powerful, but of the possibility of some day seeing a little more of what happens on that neighbouring world. In fact it is only a few years that we have had any hope of distinguishing these minute details, not to speak of explaining them. * * * * * Now, this is what happened. The map of the planet Mars was made with infinite care by the able astronomer of Milan. One sees on this chart in several regions certain points where the observer has found the presence of luminous patches shining like snow illuminated by the sun. That these luminous patches are due to snow is not likely, because some are seen near the equator in the tropics as well as at higher latitudes. Nor does it seem likely that they are the tops of mountains, for they are close to the seas and arranged symmetrically to certain straight canals. Besides, several of them seem to trace out meridians and parallels of latitude, and on seeing them one involuntarily thinks of Geodesic signals. One sees triangles, squares, and rectangles. That these luminous points should have been established by engineers or astronomers on Mars is not my idea. That the 60 great rectilinear parallel canals which we admire on that planet and which establish communication between the Martian seas should be the work of the inhabitants of this neighbouring planet would be presumptuous to imagine. That is not the conclusion I would arrive at. Nature is so rich in procedure, so varied in its manifestations, so multiple and so complex in its effects, and often so strange and original in its play, that we have no right to limit its mode of action. But it is none the less true that if the inhabitants of Mars wished to send us any signals, that method of procedure would be one of the simplest and it is in fact the only one which has been devised among ourselves. They could not do better than thus dispose luminous points at certain distances according to geometrical figures. For instance, one finds the intersection of the 267th meridian with the 14th degree of northern latitude a region limited by points situated at distances from each other corresponding to Amiens, Orleans, and Le Mans. If the inhabitants of Mars wished to send us signals they could not have chosen better places for their luminous stations. I am far from saying that this is so and that there is any intention in this arrangement. Yet if it were so, it would be we who did not understand.