“The sky is so close to the sea that it is difficult to tell which is reflected in the other, which one needs the other, which one is dominating the other.”

Canto I, line 131
Hudibras, Part I (1663–1664)
Context: Whatever sceptic could inquire for,
For ev'ry why he had a wherefore;
Knew more than forty of them do,
As far as words and terms cou'd go.
All which he understood by rote
And, as occasion serv'd, would quote;
No matter whether right or wrong,
They might be either said or sung.
His notions fitted things so well,
That which was which he could not tell;
But oftentimes mistook th' one
For th' other, as great clerks have done.

From a letter to Robert W. Gordon (February 4, 1925)
Letters

What Maisie Knew.
Prefaces (1907-1909)

Source: Commonplace Book (1985), p. 76

The Enchiridion (c. 135)
Variant: Everything has two handles, one by which it may be borne, the other by which it may not.
Context: Everything has two handles, the one by which it may be carried, the other by which it cannot. If your brother acts unjustly, don't lay hold on the action by the handle of his injustice, for by that it cannot be carried; but by the opposite, that he is your brother, that he was brought up with you; and thus you will lay hold on it, as it is to be carried. (43).

Source: Drums of Autumn

Il y a deux amours: celui qui commande et celui qui obéit; ils sont distincts et donnent naissance à deux passions, et l’une n’est pas l’autre.
Part I, ch. XXI.
Letters of Two Brides (1841-1842)

Source: 1980s, The Ecstasy of Communication (1987), p. 65