This is post I am copying from Bawa, a briliant Art of Living teacher. This is what he said..
On the day (night) of Ganesh Chathurti, we are warned not to look at the moon... Mythology says that if you look at the moon on this night, then you will get blamed for something you didn't do!
So don't look at the moon!!!
This particular belief sounds quite odd... What if the rays of the moon touch you? Will you still get blamed? If you look at the reflection of the moon in water: You are not looking up at the sky, you are looking down and there it is... in the puddle of water! What then?!
Well, at least this Ganesh Chathurti, we in Bangalore Ashram were spared from the naughtiness of the moon... the sky was overcast and there was no chance to see the moon... but no one was taking any chances, everyone was walking about focused intently on the ground :)
Is there some deeper meaning to this? You bet there is!
The moon symbolizes the mind... Just as the moon waxes and wanes, the mind goes up and down... Some days it makes you feel good, other times it can drag you down into the pits of despair for the smallest of reasons... The mind is what constantly gets you into trouble...
Ganesha is the Lord of Wisdom and it is He who teaches us how to get over the vagrancies of the mind, how to be established firmly in Knowledge and let nothing shake us out from the Bliss of the Being. And so on the day when we are going to celebrate Lord Ganesha, we don't look at the moon... meaning Follow Knowledge, not your little mind!
Don't look at the moon! Don't let that small mind of yours rule you... Be in Knowledge, Be wise, Be happy!
Brilliant, isn't it??