The Jewish People only needed forty-nine days to reach the heights of Sinai because they took the impurity that had encrusted them in Egypt and turned it into a positive force. They literally turned it on its head. In other words, each day was not an eradication of a certain aspect of evil, rather it was the transformation of that evil into its positive equivalent. The power of thought is that it can be instantly reversed. If you throw a car into reverse, you'll break the gearbox, but you can change your mind in a second.
Thought is a straight line.
A straight line connects two opposite ends of the same possibility. The polarity can be instantly reversed. Maybe this is the secret power of the month of Iyar , the month of the vav , the month of the straight line. The straight line parallels the power of thought to instantly reverse itself. And that was the very essence of the process by which the Jewish People made it to Sinai in 49 days.