He talks in a slightly accusatory and officious blurt as if he knows that his meaning will have to barge through several layers of prejudice to be heard.
After making a minor adjustment to the device, he opened a stopcock leading into one of the cylinders and the witnesses heard a hiss as of escaping air.
Therefore, whatever you have said in the dark shall be heard in the light, and what you have whispered in private rooms shall be proclaimed upon the housetops.