Darkling Words

From Dark Passage, a sign in the autopsy room of an abandoned New York mental hospital.

The complete message is,

Let Conversation
Cease. Let Laughter
Flee. This is the Place
Where Death Delights
To Help the Living.

This seems to be a common line among medical examiners and forensic specialists, old enough to have been originally written in Latin:

Taceant colloquia. Effugiat risus. Hic locus est ubi mors gaudet succurrere vitae.

But I can't determine the source.