Sunday night is the 15th of Av, a festive day on which we don’t say Tachanun. The mishna at the end of Taanit mentions the various joyful customs and historical events which took place on this day in past generations. Among these is that from this day on they would stop cutting wood for the Temple altar, since “from the 15th of Av the strength of the sun ebbs” and therefore the wood cut afterwards was not dry enough.
The gemara then adds: “From then on, anyone who adds, adds; anyone who doesn’t add, ends”. This expression, a saying of Hillel found in the mishna (Avot 1:13), refers to Torah study. The connection to Tu beAv and the wood is as follows: As the nights lengthen and the exhausting summer sun begins to burn a little less intensely, we are required to exploit this opportunity to increase Torah study, which is principally learned at night. (Yoreh Deah 246:23.)
The gemara states in a number of places that “One who studies Torah at night, a strand of loving kindness is drawn over him during the day”. What is the special blessing of nighttime study? The Iyun Yaakov commentary by Rav Yaakov Reischer (on Chagiga 12b) explains that Torah learned at night is truly Torah for its own sake; during the daytime a person may be studying so that others see him, but nighttime learning takes place in modesty and seclusion.
This explanation of Rav Reischer fits in particularly well with the context of this directive. First, the context of the mishna. Two other sayings from the same mishna in Avot also refer to modesty in study: the first is “One who draws his name, loses his name”. The commentators explain that “drawing” the name refers to seeking or attaining fame, meaning that one’s name is spread far and wide. The other is “One who makes use of the crown is lost”; a Torah scholar shouldn’t seek personal benefit from his status. (Beyond the measure dictated by law and custom; outstanding Torah scholars are rightfully due a number of privileges, such as precedence in selling their merchandise and release from certain taxes.)
This explanation also suits the context of the gemara in Taanit. Immediately preceding the passage we cited, the gemara states that the 15th of Av was the day that those killed in the attack on Beitar were finally buried; Tu beAv brought these individuals the dignity of being covered up after a long period of exposure. And immediately afterwards, we learn that the special dances held on Tu beAv in order to help singles find suitable partners were carried out in borrowed garments in order not to embarrass any young lady who lacks an appropriate outfit. The common denominator is modesty and dignity.
From Tu beAv onward, we should all strive to increase the amount of daily Torah study, even if only a small amount. At the same time we should redouble our efforts to study Torah for its own sake, not in order to make a display to others.