Nay, number (itself) in armies importeth not much, where the people is of weak courage; for (as Virgil saith) It never troubles a wolf how many the sheep be.

Francis Bacon (1561-1626) English philosopher, scientist, author, statesman

Essays or Counsels Civil and Moral, No. 29 “Of the True Greatness of Kingdoms and Estates” (1612)
    (Source)

The wolf reference is actually a common Latin proverb: "Non curat numerum lupus [The wolf doesn't care about the number]," or its longer form "Lupus non curat numerum ovium" [The wolf does not care about the number of sheep.].

Though Bacon explicitly notes the phrase in Virgil's Eclogues, the Latin saying is often attributed to Bacon.