Thinking back to the dictatorial imperial system, "worshipping Heaven" was a special privilege reserved for the Son of Heaven (the Emperor). in the Ching dynasty, there was still the regulation that any ordinary person caught worshipping Heaven directly would be punished with 80 strokes of the rod, so that common folk had no choice but to worship in secret.
遙想從前帝王專制時代，「祭天」是「真命天子」的專利，直到清朝，還有百姓拜祭天地要「杖八十」的規定，逼得升斗小民只能偷偷摸摸地拜。