“Grasp the subject, the words will follow.”
Rem tene, verba sequentur.
Cato's advice to orators (as quoted in Julius Victor, Art of Rhetoric. p. 197, Orell.; see also Wilhelm Sigismund Teuffel, Teuffel's History of Roman literature, Vol. 1 (1873), p. 158)
Cf. Dionysius Halicarnassensis, De Isocrate, ch. 12: "βούλεται δὲ ἡ φύσις τοῖς νοήμασιν ἕπεσθαι τὴν λέξιν, οὐ τῇ λέξει τὰ νοήματα." [Νature has it that style is in the service of thought, not the other way around.]
Variant translations:
Stick to your subject, and words will follow.
Get hold of the matter, the words will come of themselves.
Lay hold of the subject, and the words will follow.
Keep to the subject and the words will come.
Grasp the point, the words will follow.
Seize the subject; the words will follow.
Stick to the point; the words will follow.
Master the facts; the words will follow.
Lay hold of the substance, the words will follow.
Hold fast to the matter, the words will come.
Hang onto your meaning, and the words will come.
Have a grip of your theme and the words will come.
Hold the idea and the words will follow.
Stick to the meaning, and the words will take care of themselves.
