Have you ever felt love?Did you need scientific proof of this? How would you have definitively and scientifically proved your love existed? If you could not prove it, would that mean your love didn't exist? What would you trust: your own feelings, or science?

Demonstrative proof is lacking, but if we thought only about those things about which such proof were available, our minds would be empty most of the time.

History can come in handy. If you were born yesterday, with no knowledge of the past, you might easily accept whatever the government tells you. But knowing a bit of history--while it would not absolutely prove the government was lying in a given instance--might make you skeptical, lead you to ask questions, make it more likely that you would find out the truth.

I've become like one of those people I hate, the sort who go to the museum and, instead of looking at the magnificent Brueghel, take a picture of it, reducing it from art to proof. It's not Look what Brueghel did, painted this masterpiece but Look what I did, went to Rotterdam and stood in front of a Brueghel painting!

In order to disprove the assertion that all crows are black, one white crow is sufficient.

Indeed taking all the evidence together, it is not too much to say that there is no single historic incident better or more variously supported than the Resurrection of Christ. Nothing but the antecedent assumption that it must be false could have suggested the idea of deficiency in the proof of it.

...and when is enough proof enough?

God is an hypothesis, and, as such, stands in need of proof: the onus probandi rests on the theist.

Einer hat immer Unrecht: aber mit zweien beginnt die Wahrheit. Einer kann sich nicht beweisen: aber zweie kann man bereits nicht widerlegen.

Just because an idea is true doesn't mean it can be proved. And just because an idea can be proved doesn't mean it's true.

The best way to show that a stick is crooked is not to argue about it or to spend time denouncing it, but to lay a straight stick alongside it

The first and most important field of philosophy is the application of principles such as "Do not lie." Next come the proofs, such as why we should not lie. The third field supports and articulates the proofs, by asking, for example, "How does this prove it? What exactly is a proof, what is logical inference, what is contradiction, what is truth, what is falsehood?" Thus, the third field is necessary because of the second, and the second because of the first. The most important, though, the one that should occupy most of our time, is the first. But we do just the opposite. We are preoccupied with the third field and give that all our attention, passing the first by altogether. The result is that we lie – but have no difficulty proving why we shouldn't.

That which needs to be proved cannot be worth much.

He that, in the ordinary affairs of life, would admit of nothing but direct plain demonstration would be sure of nothing in this world but of perishing quickly.