certainly reasonable acts, yet none the less of faith, for all that:
first, that his fly is not a freak of nature; next, that his lens is
symmetrically ground; then that his observation is adequate; then that
his memory has not played him false between his observing and his
recording that which he has seen. These acts are so reasonable that we
forget that they are acts of faith. They are justified by reason before
they are made, and they are usually, though not invariably, verified by
Reason afterwards. Yet they are, in their essence, Faith and not Reason.

So, too, when a child learns a foreign language. Reason justifies him in
making one act of faith that his teacher is competent, another that his
grammar is correct, a third that he hears and sees and understands
correctly the information given him, a fourth that such a language
actually exists. And when he visits France afterwards he can, within
limits, again verify by his reason the acts of faith which he has
previously made. Yet none the less they were acts of faith, though they
were reasonable. In a word, then, no acquirement of or progress in any
branch of human knowledge is possible without the exercise of faith. I
cannot walk downstairs in the dark without at least as many acts of
faith as there are steps in the staircase. Society could not hold
together another day if mutual faith were wholly wanting among its
units. Certainly we use reason first to justify our faith, and we reason
later to verify it. Yet none the less the middle step is faith. Columbus
reasoned first that there must be a land beyond the Atlantic, and he
used that same reason later to verify his discovery. Yet without a
sublime act of faith between these processes, without that almost
reckless moment in which he first weighed anchor from Europe, reason
would never have gone beyond speculative theorizing. Faith made real for
him what Reason suggested. Faith actually accomplished that of which
Reason could only dream.