By being all things to all spies, one does rather run the risk of
becoming nothing to oneself," he confessed sadly. "Please don't
ever imagine you'll be unscathed by the methods you use. The
end may justify the means -- if it wasn't supposed to, I dare say
you wouldn't be here. But there's a price to pay, and the price does
tend to be oneself. Easy to sell ones soul at your age. Harder
later."
-- John le Carré.
The Secret Pilgrim.
(novel, 1990), Chapter 1.