Our Better Halves
The second perek of Maseches Megillah starts by discussing the laws of someone who read the Megillah l’mafreiah. If someone read the Megillah out of order, he has not fulfilled his obligation. The Kotzker Rebbe offered a homiletic interpretation. Someone who reads the Megillah simply as a story from the past has not fulfilled his obligation. The reader must apply the lessons learned from the Megillah to the present. Divine Providence is constantly guiding current events, though it may not be readily apparent. A person who fails to see the application to his life has failed to fulfill the intent of the Megillah reading.
The Gemara proceeds to apply a similar law to Hallel. If someone reads Hallel out of order, he has not fulfilled his obligation. This certainly applies to one who reads the verses in any given paragraph out of order. Many Acharonim take this halachah further and are of the opinion that even if one reads the paragraphs of Hallel out of order he has not fulfilled his obligation. (MB 422:26).
The Chofetz Chaim finds it peculiar that the Shulchan Aruch chose to codify this law about the recitation of Hallel in the midst of other Rosh Chodesh laws. The recitation of Hallel on Rosh Chodesh is purely based on custom. On any day when the recitation of Hallel is mandated, full Hallel must be recited. A custom developed to recite Hallel on other days as well. To differentiate those days from the days when Hallel is mandated, verses are skipped. On Rosh Chodesh, for example, only half-Hallel is recited. Actually, half-Hallel is a misnomer; “85% Hallel” would be more accurate. We simply skip 22 pesukim from the complete Hallel. When we recite half-Hallel, we don’t say the first 11 pesukim of chapters 115 and 116, but we do recite the remainder. The import of half-Hallel is that it is the Hallel that contains some half-chapters, not that it is half of the original Hallel.