We have explained in our article Biblical Formatting located on the world wide web at http://www.Rashiyomi.com/biblicalformatting.pdf, that the Biblical Author indicated bullets by using repeating keywords.

That is, if a modern author wanted to get a point across using bullets - a list of similar but contrastive items - then the Biblical Author would use repeating keywords. Today's verse illustrates this principle.

Bullets whether indicated through modern notation or through the Biblical method of repeating keywords always indicate contrastive emphasis - that is, each bullet is presumed to be a distinct item contrasted to the other items on the list. Very often the bullets are also used to indicate that the entire list of exhaustive of some spectrum.

Verse(s) Ex10-22:23 discussing the 9th plague, the plague of darkness, states And Moses stretched out his hand toward heaven;
• and there was a thick darkness in all the land of Egypt three days;
• They saw not one another, nor any rose from his place for three days;
The repeated underlined phrase three days creates a bullet effect. The bullet effect in turn creates an emphasis on the distinctness of all enumerated items. Rashi interprets the distinctness as follows As the bullets show there were two sets of three days. During the first three days there was dark fog; during the 2nd 3 days the darkness intensified to the extent that visibility was zero, even close up, and one could not even find one's seat to sit down.

Advanced Rashi: Rashi also devotes time to explaining that God brought a plague of darkness so that the Egyptians would not know that the non-believing Jews were dying out and being buried. However this is a secondary point in Rashi and therefore we are not discussing it today.