Quamquam enim hanc spes non exigua visa est affulsisse, lubricus tamen quem prae manibus (habemus Proteus tam hic quam superius non raro elapsus, spem fefellit).
"Although no small hope seemed to shine, what we have in hand is slippery, like Proteus, who (in the same way, often escaped, and disappointed hope)."
On squaring the circle.
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