Chasidut for Rosh Hashanah 1:15

And the Fifteenth of the month is the [New Year for Trees] according to Beit Hillel, who come from the side of Kindness and Love. Therefore [for Beit Shammai] the Mishnah (Rosh Hashanah 1:1) says “like the House of Shammai” using a Chaf to mean “like.” Understand these allusions.