Full Idea
Act in such a way that you always treat humanity whether in your own person or in the person of any other, never simply as a means, but always at the same time as an end.
Gist of Idea
Always treat yourself and others as an end, and never simply as a means
Source
Immanuel Kant (Groundwork of the Metaphysic of Morals [1785], AA429 p.96), quoted by Terry Pinkard - German Philosophy 1760-1860 02
Book Reference
Pinkard,Terry: 'German Philosophy 1760-1860' [CUP 2002], p.53
A Reaction
This sets up the Kingdom of Ends. Note that this does not prohibit using people as a means. It just asks you to respect waiters and shop assistants. It seems to say you should not treat 'your own person' merely as a means. Prostitution?