Opus Majus is a significant work by the medieval scholar Roger Bacon, written in the 13th century. It is a comprehensive treatise that covers various subjects, including philosophy, science, and mathematics. Bacon aimed to promote the use of empirical observation and experimentation in understanding the natural world. The text is divided into several parts, each addressing different areas of knowledge, such as optics, alchemy, and linguistics. Opus Majus is notable for its early advocacy of the scientific method, emphasizing the importance of observation and evidence in the pursuit of knowledge.