The cost of a thing is the amount of life you exchange for it, Thoreau wrote.

An average house near him cost perhaps $800: at $1 a day, 800 days of work.

Saving it, he reckoned, took ten to fifteen years of a laborer's life.

On 4 July 1845 he moved into a cabin he built by Walden Pond.

Ten feet by fifteen. He listed every material he paid for.

In all, $28.12½: about 28 days' wages at $1 a day.

A student's room at Cambridge College rented for $30 a year.

His whole house cost less than one year's rent.

His food cost about 27 cents a week.

By working about six weeks a year, he met all the expenses of living.

His winters, and most of his summers, were free and clear for study.