(Editor's note: Kent Harrington, a former senior CIA analyst, served as National Intelligence Officer for East Asia, Chief of Station in Asia and the CIA's Director of Public Affairs.) Metastasis: The spread of cancer cells from the place where they first formed to another part of the body. That's from the National Cancer Institute. Substitute the word "lies" for "cancer cells" and add "politic" after "body" and the definition describes another disease equally well: How presidential mendacity infects a democracy. It's not a metaphor. President Trump made that clear himself.