It is widely believed that a group of ancient treatises, called Chitrasutra, laid down the rules for painting, including those of the depiction of seasons. In their defining book “An Early Document of Indian Art” (1976), B.N. Goswamy and A.L. Dahmen-Dallapiccola wrote, “Unfortunately, because of the Sanskrit original (of the early chitrasutras, called chitralakshana) having been lost, it is not possible to draw any conclusions regarding dating on the evidence of language and style. All things considered, however, we feel that the work may roughly be assigned to the early Gupta period…”