All sensuality is one, though it takes many forms; all purity is one. It is the same whether a man eat, or drink, or cohabit, or sleep sensually. They are but one appetite, and we only need to see a person do any one of these things to know how great a sensualist he is. The impure can neither stand nor sit with purity.
The Writings of Henry David Thoreau: With Bibliographical Introductions and Full Indexes (ed. 1894)