Poirot thought it not quite professional to begin a routine working day before ten. - Agatha Christie

For in the long run, either through a lie, or through truth, people were bound to give themselves away …

Nobody understands the art of living nowadays,... Catching trains, making appointments, fixing times for everything — all nonsense. Get up with the sun I say, have your meals when you feel like it, and never tie yourself to a time or a date. I could teach people how to live if they would listen to me.

If you confront anyone who has lied with the truth, they usually admit it — often out of sheer surprise. It is only necessary to guess right to produce your effect.