折疑論 2.139

2.139

不知有出告反面之道。冬溫夏凊之儀（告音孤。申上文。禮記云。出必告。註以知去處也。反必面。註回家見於親。不敢使親之有望也。冬則令暖父母之枕蓆。夏則扇清枕蓆之以涼。上古之時皆無此儀）。

They did not know the way of reporting when going out and presenting oneself upon return, nor the etiquette of warming in winter and cooling in summer (gao is pronounced gu, elucidating the above text. The Book of Rites says: 'When going out, one must report,' the commentary notes: so that parents know where one is going; 'upon returning, one must present oneself,' the commentary notes: returning home to see one's parents, not daring to let parents be left waiting. In winter, one warms the parents' pillow and mat; in summer, one fans the pillow and mat to make them cool. In high antiquity, none of these etiquettes existed).