Lamentations Rabbah on the Joy of Yom Kippur and the Fifteenth of Av

[There were no happier days for Israel than the fifteenth of Av and Yom Kippur.] Granted [that this is so] with respect to Yom Kippur, since it is a day of pardon and atonement for Israel and the day on which the second set of tablets [of the Ten Commandments] was given, but why [is this so with respect to] the fifteenth of Av? R. Jacob bar Aḥa said in the name of R. Assi: Because that day begins the favorable season for cutting down trees [to fuel the sacrificial fires in the Temple], for all the wood that is cut down then does not become grub-eaten.