The greeting from Rosh Hashanah on is Leshanah tovah tichateimu, may you be sealed for a good year. This is in reference to the image of the 'book of life'. According to this analogy or image, G-d sits in judgement on us at Rosh Hashanah, and writes our name and fate in the book of life. Then, we have some time, the period of the yamim nora'im (days of awe) to affect the 'sentence' by our behavior - through sincere repentance, acts to repair injuries we have caused and to seek forgiveness of those we have hurt, and finally to resolve not to repeat our misdeeds. On Yom Kippur, at the end of the Neilah (concluding) services, as full darkness approaches, we imagine that the gates of Heaven are 'closing' to our pleas, and when they close, the book of life will be sealed with the judgement as it is written at that moment. It is an awesome, perhaps even terrifying image.
Because we believe that G-d is merciful, it is not the death of sinners that G-d seeks, but their repentance and return to the proper way. In that sense, we know that it is within the power of every person to 'change' the judgement - to at the least mitigate the severity of that imagined fate written in that metaphorical book of life. And because we believ that all people seek to live and to have a good life, we think that everyone will do all that is within their power to make the judgement as positive as possible. For that reason, we speak and think as if the judgement will be for a good fate, and we wish each other that this good judgement will be 'sealed' in the book of life, left intact and positive, and followed in the year ahead of us.
So may you be sealed for a good year in 5767.
Rabbi Joe Blair
Oct 3 2006