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.