Manu

“ Those (only, who) know that the holy day of Brahman, indeed, ends after (the completion of) one thousand ages (of the gods) and that his night lasts as long, (are really) men acquainted with (the length of) days and nights.
74. At the end of that day and night he who was asleep, awakes and, after awaking, creates mind, which is both real and unreal.
75. Mind, impelled by (Brahman's) desire to create, performs the work of creation by modifying itself, thence ether is produced; they declare that sound is the quality of the latter. ”

“ The sun divides days and nights, both human and divine, the night (being intended) for the repose of created beings and the day for exertion.
66. A month is a day and a night of the manes, but the division is according to fortnights. The dark (fortnight) is their day for active exertion, the bright (fortnight) their night for sleep.
67. A year is a day and a night of the gods; their division is (as follows) : the half year during which the sun progresses to the north will be the day, that during which it goes southwards the night. ”

“ All plants, propagated by seed or by slips, grow from shoots; annual plants (are those) which, bearing many flowers and fruits, perish after the ripening of their fruit;
47. (Those trees) which bear fruit without flowers are called vanaspati (lords of the forest) ; but those which bear both flowers and fruit are called vriksha.
48. But the various plants with many stalks, growing from one or several roots, the different kinds of grasses, the climbing plants and the creepers spring all from seed or from slips. ”

“ One set of duties (is prescribed) for men in the Krita age, different ones in the Treta and in the Dvapara, and (again) another (set) in the Kali, in a proportion as (those) ages decrease in length.
86. In the Krita age the chief (virtue) is declared to be (the performance of) austerities, in the Treta (divine) knowledge, in the Dvapara (the performance of) sacrifices, in the Kali liberality alone.
87. But in order to protect this universe He, the most resplendent one, assigned separate (duties and) occupations to those who sprang from his mouth, arms, thighs, and feet. ”

“ Manu is considered a law giver in the Hindu tradition. Manu Smriti is one of the 18 Smritis. It is important to note that laws given by Manu, in Manu Smriti although followed in some form even today, are not considered divine, and may be modified by the society to keep up with the times. Indeed, it has been speculated that in its current form, Manu Smriti represents laws that have been added or modified throughout the history. ”