„Worry does not empty tomorrow of its sorrow, it empties today of its strength.“

As quoted in Today's Gift : Daily Meditations for Families (1985) by Hazelden Publishing, p. 11

This is a quotation from "The Old Man's Relapse", a poem addressed to Edward Young, but written by Lord Melcombe.
Misattributed

Book I, line 469 (tr. E. Ridley).
Pharsalia

Source: Traveling Light: Releasing the Burdens You Were Never Intended to Bear

Vacancy
Song lyrics, Verities & Balderdash (1974)

Source: The Sisterhood of the Traveling Pants

Source: Evermore

Fragments of Melissus's On Nature, Fragment 7
Original: (el) Οὐδ᾿ ἂν τὸ ὑγιὲς ἀλγῆσαι δύναιτο· ἀπὸ γὰρ ἂν ὄλοιτο τὸ ὑγιὲς καὶ τὸ ἐόν, τὸ δὲ οὐκ ἐὸν γένοιτο. Καὶ περὶ τοῦ ἀνιᾶσθαι ὡυτὸς λόγος τῶι ἀλγέοντι. Οὐδὲ κενεόν ἐστιν οὐδέν· τὸ γὰρ κενεὸν οὐδέν ἐστιν· οὐκ ἂν οὖν εἴη τό γε μηδέν. Οὐδὲ κινεῖται· ὑποχωρῆσαι γὰρ οὐκ ἔχει οὐδαμῆι, ἀλλὰ πλέων ἐστίν. Εἰ μὲν γὰρ κενεὸν ἦν, ὑπεχώρει ἂν εἰς τὸ κενόν· κενοῦ δὲ μὴ ἐόντος οὐκ ἔχει ὅκηι ὑποχωρήσει.

Source: How to Stop Worrying and Start Living (1948), p. 237. Part 8 : How I Conquered Worry,

Kandinsky's last theoretical statement (Paris, 1942); in Kandinsky, Frank Whitford, Paul Hamlyn Ltd, London 1967, p. 38
1930 - 1944

Act II, scene ii.
Rollo, Duke of Normandy, or The Bloody Brother, (c. 1617; revised c. 1627–30; published 1639)

Came from an online quiz falsely attributed to Schulz http://www.snopes.com/glurge/schulz.asp. However, in the 13 June 1980 Peanuts strip http://www.gocomics.com/peanuts/1980/06/13, Marcie does say "I promise there'll be a tomorrow, sir. In fact, it's already tomorrow in Australia."
Misattributed

Source: Love and Will (1969), Ch. 1 : Introduction : Our Schizoid World, p. 32
Context: The constructive schizoid person stands against the spiritual emptiness of encroaching technology and does not let himself be emptied by it. He lives and works with the machine without becoming a machine. He finds it necessary to remain detached enough to get meaning from the experience, but in doing so, to protect his own inner life from impoverishment.

A Conversation with Ward Cunningham (2003), To Plan or Not To Plan
Context: To worry about tomorrow is to detract from your work today. Time you spend thinking about tomorrow is time you're not spending thinking about what to do today. The place you leave in the code because you think you'll need it tomorrow, is actually a waste of time today — and a liability tomorrow. It does more harm than good.

Kosmos (1932), Above is Beginning Quote of the Last Chapter: Relativity and Modern Theories of the Universe -->