Today we ask the database query: What does the number 40 symbolize? The query uncovers 5 examples. An examination of these examples justifies the Rashi assertion that 40 symbolizes an EMBRYONIC period during which development to new horizons can take place. The table below presents results of the query along with illustrations of Rashi's comment.

Advanced Rashi: Rashi literally says: 40 days of flood corresponding to the 40 days in which the foetus is formed. They sinned by burdening God to create foetii to adulterous unions and were punished with 40 days of flood. My opinion is that the major driving force behind the Rashi is the database query which shows that in general 40 corresponds to an embryonic development to a new horizon. I therefore regard Rashi as adding another nuance to the 40 days applicable to this particular case, the flood. Rashi points out that the embryo takes 40 days to develop. Rashi further shows the Divine Justice in the irony that the 40 days during which embryos from adulterous unions were being produced corresponded to the 40 days of punishment. We however regard this Rashi comment as secondary and the above database analysis as primary. Very frequently Rashi will rely on the teacher to present primary meaning and will suffice with indicating an unexpected seconday nuance. I beleive this is the proper way to take this Rashi.