“Edible fruits? Yes, possibly; and animals or something more or less like animals to feed upon them. But even if there are such, which planetoscopists doubt, they must be very different creatures in form and function from any we know on this one small world of ours. For just consider, Frida, what we mean by life. We mean a set of simultaneous and consecutive changes going on in a complex mass of organised carbon compounds. When most people say 'life,' however,--especially here with you, where education is undeveloped--they aren't thinking of life in general at all (which is mainly vegetable), but only of animal and often indeed of human life. Well, then, consider, even on this planet itself, how special are the conditions that make life possible. There must be water in some form, for there's no life in the desert. There must be heat up to a certain point, and not above or below it, for fire kills, and there's no life at the poles (as among Alpine glaciers), or what little there is depends upon the intervention of other life wafted from elsewhere--from the lands or seas, in fact, where it can really originate. In order to have life at all, as WE know it at least (and I can't say whether anything else could be fairly called life by any true analogy, until I've seen and examined it), you must have carbon, and oxygen, and hydrogen, and nitrogen, and many other things, under certain fixed conditions; you must have liquid water, not steam or ice: you must have a certain restricted range of temperature, neither very much higher nor very much lower than the average of the tropics. Now, look, even with all these conditions fulfilled, how diverse is life on this earth itself, the one place we really know--varying as much as from the oak to the cuttle-fish, from the palm to the tiger, from man to the fern, the sea-weed, or the jelly-speck. Every one of these creatures is a complex result of very complex conditions, among which you must never forget to reckon the previous existence and interaction of all the antecedent ones. Is it probable, then, even a priori, that if life or anything like it exists on any other planet, it would exist in forms at all as near our own as a buttercup is to a human being, or a sea-anemone is to a cat or a pine-tree?” “Well, it doesn't look likely, now you come to put it so,” Frida answered thoughtfully: for, though English, she was not wholly impervious to logic.