To be liable for writing on Shabbos, one must write two letters that endure, which generally means they spell a word. One example is Shem, a name made from the first two letters the longer name Shimon. But the middle mem in Shimon is not the same as the final mem in Shem. We learn these letters can be interchanged from the hidden reference to mayim, water, and the water libations of Sukkot in Numbers 29:19,31,33. The final mem is an “upgrade” from the middle mem because it is closed, and the subject of a little miracle in the original tablets of the Ten Commandments. We can learn many lessons from the letters themselves, including the importance of charity, and the way God waits for the wicked to turn around and seek atonement. An especially lovely lesson is how easy it is to create a falsehood (sheker – made from three consecutive letters in the alef-bet) and how much harder to create truth (emet, made from the first, middle and last letters of the alef-bet). The letters of emet, however, all stand on two legs, while the letters of sheker all stand on one leg – truth is eternal. To be liable, the letters must be written with with a substance and in a manner that endures. If one writes a single letter that completes a scroll, one not is liable for writing, but rather for makeh b’patish – striking the final blow.