I'm currently working on a paper about Sappho and Murasaki Shikibu and how their lives shaped the mind in their retrospective cultures. Could you help me out on how Murasaki did this?
Do you mean how their culture shaped their minds, or the minds of people in their day, or of people in general (throughout time) in their cultures? For Murasaki, find the book The World of the Shining Prince: Court Life in Ancient Japan, by Ivan Morris. What you should remember is that as a member of the court, and Japanese elite, her views and the lifestyle she wrote about solely reflect this environment. You certainly should discuss the status of educated women in Heian Japan - why they were more successful than men in producing literature that was widely received by the Japanese and why it has lasted. She has written a diary, "The Murasaki Shikibu Diary" from which excerpts can be found. The Diaries of Court Ladies of Old Japan by Annie Omori and Doi Dochi, AMS Press, 1970 would help. Letters and diary writing among the ladies of the court were instrumental in the development of prose writing, especially the form of "poem tales" which were a type of poetic biography - a mixture of fact and fiction.
Women who wrote, like Murasaki, found a main audience in women - ladies of the court and the wives and daughters of courtiers. By writing in Japanese prose, while men tended to write in classical Chinese, it was women who popularized the art of Japanese prose.
Also, most versions of Murasaki's The Tale of Genji will give you some insights into the effect of her writing on the Japanese.
P.S. - Your plan to compare Sappho and Murasaki sounds very interesting. Don't forget the Japanese fascination with expressing themselves through poems - often composed at the spur of the moment. Murasaki was known to be very accomplished at this skill upon which both men and women were judged.