“When the only tool you have is a hammer, all problems begin to resemble nails”

“When the only tool you have is a hammer, all problems begin to resemble nails”

I think that this quote refers to how the way that you see things limits what you see. So for example, if sense perception was the "hammer", then that way of knowing would limit the knowledge that a person could obtain through that way of knowing, so the person would only be able to see the "nails". Also, a philosopher named Ludwig Wittgenstein was well known for his philosophy of the limits on sense perception.

“Tell me,” he asked a friend, “why do people always say, it was natural for man to assume that the sun went round the earth rather than that the earth was rotating?” His friend replied, “Well, obviously because it just looks as though the Sun is going round the Earth.” Wittgenstein replied, “Well, what would it have looked like if it had looked as though the Earth was rotating?"

Here Wittgenstein's remark exemplifies the quote with the hammer and nails. Wittgenstein implies that sometimes sense perception can distort the way that we perceive knowledge. The quote with the hammer and nails reflects that ways of knowing, such as sense perception, can change the way we see things.