I see men with infinite pains endeavoring to realize to their bodies, what I, with at least equal pains, would realize to my imagination,—its capacities; for certainly there is a life of the mind above the wants of the body, and independent of it. Often the body is warmed, but the imagination is torpid; the body is fat, but the imagination is lean and shrunk.
 Henry David Thoreau, A Week on the Concord and Merrimack Rivers (1849). copy citation

Context

“In short, the history which we read is only a fainter memory of events which have happened in our own experience. Tradition is a more interrupted and feebler memory. This world is but canvas to our imaginations. I see men with infinite pains endeavoring to realize to their bodies, what I, with at least equal pains, would realize to my imagination,—its capacities; for certainly there is a life of the mind above the wants of the body, and independent of it. Often the body is warmed, but the imagination is torpid; the body is fat, but the imagination is lean and shrunk. But what avails all other wealth if this is wanting? “Imagination is the air of mind,” in which it lives and breathes. All things are as I am. Where is the House of Change? The past is only so heroic as we see it.” source