“The only impossible thing is something to be impossible.”

A Bridge for Passing (1962)

The alchemist, p. 141.
Variant: There is only one thing that makes a dream impossible to achieve: the fear of failure.
Source: The Alchemist (1988)

Source: Eat, Pray, Love

Source: Mini Shopaholic

Si le grain ne meurt [If It Die] (1924), ch. III
Source: Autumn Leaves

The Book of Tea

Interview with Joan Gordon
Context: There’s simultaneously something rigorous and something playful in genre. It’s about the positing of something impossible—whether not-yet-possible or never-possible—and then taking that impossibility and granting it its own terms and systematicity. It’s carnivalesque in its impossibility and overturning of reality, but it’s rationalist in that it pretends it is real. And it’s that second element which I think those who dip their toes in the SF pond so often forget. They think sf is “about” analogies, and metaphors, and so on. I refute that—I think that those are inevitable components, but it’s the surrendering to the impossible, the weird, that characterizes genre. Those flirting with SF don’t surrender to it; they distance themselves from it, and have a neon sub-text saying, “It’s okay, this isn’t really about spaceships or aliens, it’s about real life,” not understanding that it can be both, and would do the latter better if it was serious about the former.

Source: Letters from the Earth: Uncensored Writings
Source: Mark Twain's Notebook (1935), p. 381

Source: His Dark Materials, The Subtle Knife (1997), Ch. 4 : Trepanning