Are physical forces alone at work there, or has evolution begotten something more complex, something not akin to what we know on Earth as life? It is in this that lies the peculiar interest of Mars.

Bright points in the sky or a blow on the head will equally cause one to see stars.

Formulae are the anaesthetics of thought, not its stimulants and to make any one think is far better worth while than cramming him with ill-considered, and therefore indigestible, learning.

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.

Ever since celestial mechanics in the skillful hands of Leverrier and Adams led to the world-amazed discovery of Neptune, a belief has existed begotten of that success that still other planets lay beyond, only waiting to be found.

Are physical forces alone at work there, or has evolution begotten something more complex, something not akin to what we know on Earth as life? It is in this that lies the peculiar interest of Mars.

Imagination is as vital to any advance in science as learning and precision are essential for starting points. Let me warn you to beware of two opposite errors: of letting your imagination soar unballasted by facts, but on the other hand, of shackling it so solidly that it loses all incentive to rise.