Question mark
The rhetorical question mark or percontation point was invented by Henry Denham in the 1580s and was used at the end of a rhetorical question; however, its use died out in the 17th century. It was later revived in modern-day society by Matt DiRoberto. It was the reverse of an ordinary question mark, so that instead of the main opening pointing back into the sentence, it opened away from it. This character can be represented using the reversed question mark (⸮) found in Unicode as U+2E2E. The percontation point is analogous to the irony mark, but those are even more rarely seen.
Q source
In 1838 another German, Christian Hermann Weisse, took Schleiermacher's suggestion of a sayings source and combined it with the idea of Markan priority to formulate what is now called the Two-Source Hypothesis, in which both Matthew and Luke used Mark "and" the sayings source. Heinrich Julius Holtzmann endorsed this approach in an influential treatment of the synoptic problem in 1863, and the two-source hypothesis has dominated ever since.