The present inhabitation of Mars be a race superior to ours is very probable.

— Camille Flammarion, French astronomer and founder of the French Astronomical Society, 'La planète Mars et ses conditions d'habitabilitè, 1892.

It is well to fetter the wings of our fancy and restrain its flights. It is quite possible we may have formed entirely erroneous ideas of what we actually see. The greenish gray patches may not be seas at all, nor the ruddy continents, solid land. Neither may the obscuring patches be clouds of vapor. Man is too quick at forming conclusions. Let him but indistinctly see a thing, or even be undecided as to whether he does actually see it and he will then and there set himself to theorizing, and build immense castles of conjecture on a foundation, of whose existence he is by no means certain.

— Edward Emerson Barnard, 'Mars: His Moons and His Heavens,' an unpublished manuscript in the Vanderbilt University Archives, 1880.

Speculation has been singularly fruitful as to what these markings on our next to nearest neighbor in space may mean. Each astronomer holds a different pet theory on the subject, and pooh-poohs those of all the others. Nevertheless, the most self-evident explanation from the markings themselves is probably the true one; namely, that in them we are looking upon the result of the work of some sort of intelligent beings. . . . The amazing blue network on Mars hints that one planet besides our own is actually inhabited now.

— Percival Lowell, address to the Boston Scientific Society, printed in the Boston Commonwealth. This was before he want to Flagstaff and viewed Schiaparelli's network of canali for himself. 22 May 1894.

Irrigation, unscientifically conducted, would not give us such truly wonderful mathematical fitness [as we observe in the Martian canals]. . . . A mind of no mean order would seem to have presided over the system we see—a mind certainly of considerably more comprehensiveness than that which presides over the various department of our own public works.

— Percival Lowell, c. 1908.

[scientists have] discovered two lesser stars, or satellites, which revolve about Mars; whereof the innermost is distant from the center of the primary planet exactly three of its diameters, and the outermost five; the former revolves in the space of ten hours, and the latter in twenty one and a half; so that the squares of their periodical times are very near in the same proportion with the cubes of their distance from the center of Mars; which evidently shows them to be governed by the same law of gravitation that influences the other heavenly bodies.

— Jonathan Swift, 'Gulliver's Travels,' the moons of Mars could not be observed at this time, 1726.

We have your satellite if you want it back send 20 billion in Martian money. No funny business or you will never see it again.

— Reportedly on a wall in a hall at NASA's Jet Propulsion Lab, California, after losing contact with the Mars Polar Lander.

We are all . . . children of this universe. Not just Earth, or Mars, or this system, but the whole grand fireworks. And if we are interested in Mars at all, it is only because we wonder over our past and worry terribly about our possible future.

— Ray Bradbury, 'Mars and the Mind of Man,' 1973.

It might be helpful to realize, that very probably the parents of the first native born Martians are alive today.

— Harrison 'Jack' Schmitt.