I have now told you, dear Serenus, what can preserve peace of mind. I've explained what can restore it when you lose it. I've shown you what can stop the vices that secretly eat away at it. But remember this: none of these methods is strong enough by itself. You must watch over your restless mind with constant, intense care if you want to hold onto something so fragile.
I have now, my beloved Serenus, given you an account of what things can preserve peace of mind, what things can restore it to us, what can arrest the vices which secretly undermine it: yet be assured, that none of these is strong enough to enable us to retain so fleeting a blessing, unless we watch over our vacillating mind with intense and unremitting care.