Anadhyāya (anadhyaya) literally means ‘not to study’. Ancient Indian society fixed certain dates and events (natural as well as man-made) on or during which studying (traditional texts and knowledge) was prohibited. This act of refraining from study – in general or of a particular branch of knowledge – is called anadhyāya.

Purāṇas (Purana) vary in opinion on the reasons of anadhyāya. Anadhyāya should take place when it it storms and rains in monsoon while igniting the sacrificial fire. One should refrain from studying when one is in the company of an unprincipled person, when there is a corpse in the locality, when there is a gathering of many and when one hears the sound of moaning. Anadhyāya also should take place at the times of daily worship at dawn and dusk, and during the full moon, the new moon, the eighth and fourteenth days of a lunar calendar. One should refrain from study on the three days following the Vedic rituals of upākarma (upakarma) and utsarga. Refraining from study for a whole day has been prescribed in the case of aṣṭakā (ashtaka) and on the day marking the end of a season. Studying under the shade of the following trees has been prohibited: śleṣmātaka (sleshmataka; elephant apple), śimula (simula; red cotton), madhuka (mahua), kovidāra (kovidara; red kachnar) and kapittha (wood apple). Study is prohibited for three nights upon the death of one’s fellow students, teachers and men of one’s equal educational qualification. One should observe anadhyāya if invited to a funeral, at the times of solar and lunar eclipse, and on the starting days of Summer solstice and Winter solstice. Anadhyāya should be observed also if one follows a corpse to the crematorium, when one is undergoing the period of impurity after a birth or a death in one’s family, and when there is an earthquake. Studying other religious texts is prohibited after reading Āraṇyaka (Aranyaka), a Vedic appendix. But Vedāṅga (Vedanga), Mahābhārata (Mahabharata), Purāṇa (Purana) and other religious texts are excluded from the dominion of anadhyāya. 

If a strong wind blows at night, or there is a dusty wind in daytime, or there are extreme manifestations of natural occurrences like thunderbolts, lightning, roaring rain clouds and shower of meteors, one should observe ākālika anadhyāya (akalika anadhyaya; refrain from studies due to natural calamities). 

Anadhyāya largely referred to refraining from the studies of the Vedic literature. However, a good many practical purpose demanded some other days and occasions to be observed as anadhyāya. Even five or six decades ago the traditional Sanskrit schools used to stop giving lessons on the days of full moon, new moon and the first, eighth and fourteenth days of the lunar calendar. Studying grammar was prohibited on the night of the thirteenth day of the lunar calendar. Natural phenomena like gale, hailstorm, thunderbolts, meteor shower, solar and lunar eclipses, dust storm, fire and calls of ominous beasts and birds provided the occasions of anadhyāya, as did the artificial reasons like beginning of a battle, clanking of weapons and even the sound of music. Study had to be stopped even if a beast cut across the space between a teacher and the students while a class was going on. Besides, studying was not prescribed when there is a gathering of people at one’s home, especially on the occasion a festival. Viśiṣṭānadhyāya (visishtanadhyaya) – anadhyāya in honour of a prestigious person – used to demarcate anadhyāya on the occasion of arrival of an eminent guest at the teacher’s house. On someone’s demise in a village, anadhyāya was to be observed in a village until the funeral was over. Study was prohibited when one was unclean, impure, was busy in some other task and especially associated with some work involving funeral and crematorium. [P. 124. Hindur Achar Anushthan. Chintaharan Chakrabarty]