Thou art a little soul bearing about a corpse, as Epictetus used to say. Book IV

And how does the God's existence emerge from the proof? Does it follow straightway, without any breach of continuity? Or have we not here an analogy to the behavior of the little Cartesian dolls? As soon as I let go of the doll it stands on its head. As soon as I let it go – I must therefore let it go. So also with the proof. As long as I keep my hold on the proof, i.e., continue to demonstrate, the existence does not come out, if for no other reason than that I am engaged in proving it; but when I let the proof go, the existence is there. But this act of letting go is surely also something; it is indeed a contribution of mine. Must not this also be taken into the account, this little moment, brief as it may be – it need not be long, for it is a leap. However brief this moment, if only an instantaneous now, this "now" must be included in the reckoning. Philosophical Fragments 

To judge the appearances we receive of things, we should need a judicatory instrument; to verify this instrument, we should need a demonstration; to rectify this demonstration, we should need an instrument: so here we are arguing in a circle. Seeing the senses cannot decide our dispute, being themselves full of uncertainty, we must have recourse to Reason; there is no reason but must be built upon another reason, so here we are retreating backwards to all eternity. Essays

“Waste not your Hour, nor in the vain pursuit / Of This and That endeavour and dispute / Better be jocund with the fruitful Grape / Than sadden after none, or bitter, Fruit.” Rubaiyat of Omar Khayyam