Only make something to take the place of something, and men will behave as if it was the very thing they wanted. They must behave, at any rate, and will work up any material. There is always a present and extant life, be it better or worse, which all combine to uphold.
 Henry David Thoreau, A Week on the Concord and Merrimack Rivers (1849). copy citation

Context

“Men do not fail commonly for want of knowledge, but for want of prudence to give wisdom the preference. What we need to know in any case is very simple. It is but too easy to establish another durable and harmonious routine. Immediately all parts of nature consent to it. Only make something to take the place of something, and men will behave as if it was the very thing they wanted. They must behave, at any rate, and will work up any material. There is always a present and extant life, be it better or worse, which all combine to uphold. We should be slow to mend, my friends, as slow to require mending, “Not hurling, according to the oracle, a transcendent foot towards piety.” The language of excitement is at best picturesque merely.” source