Sea is the purest and most polluted water: for fish drinkable and healthy, for men undrinkable and harmful.
But this "proverb" caught my attention:
The road up and the road down are the one and the same.
"Paradox" is a controversial concept in Philosophy, but because it's often an important concept in understanding theology I thought Heraclitus could help us out a little. Jesus the Son of God, is both human and divine, a paradox similar to the one about the road expressed above by Heraclitus, two different things in unity. On the other hand an antinomy (a synonym for 'paradox') at the heart of Christian Theodicy is a contradiction, three opposite things (God's power, his love, and evil) held in tension. Previously I'd used "paradox" as a catch-all expression. But I think it's important to distinguish between a paradox, two or more different things in unity and a contradiction, two or more opposite things in tension.
[Heraclitus by Hendrick ter Brugghen, 1588]