400. Point of no return

This particular act by Julius Caesar while uttering the now famous phrase ālea iacta est ("the die has been cast") said to have precipitated the Roman Civil War which ultimately led to the rise of Caesar and the era of imperial Rome. What is the act which nowadays means to pass a point of no return?

399. Elementary, my dear Watson...

"It has been a while, Watson. I have been staring at these images for the last hour and they seem to make no sense at all. What will wrought them together, I wonder....Pass me my pipe, will you? And if you would be so kind enough as to fill up the syringe with the good old 7% solution. The game is afoot. Again."

398. It is all about trust

This particular type of furniture gets its name from the Italian for belief or trust. The story goes something like this. In the 16th century, food and drinks were laid out on this furniture to be tasted by a servant prior to being served to a lord or other important person (such as the pope or a cardinal) in order to test for poison. Thus, an act of trust lent its name to the room where the act took place and eventually the type of furniture. Name please!