In the old days, when people kept ledgers, they wouldn&#x27;t tally up every line from the first page of their first ledger book all the way up to the last line entered.  They would instead occasionally write a special summary line that encapsulates all the changes made since the last summary.<p>At minimum, there would be a total at the bottom of each page, which would be copied to the top of the next.  That way, you only had to deal with one page of the ledger at a time, rather than all the pages you have ever written.<p>And yet, if you really wanted to, you <i>could</i> audit every transaction you ever entered.  They were still <i>there</i>, but you didn&#x27;t need to keep track of business from 10 years ago to get things done today.<p>Is there no way for bitcoin to start a new page of its ledger by writing down the verified totals from all prior transactions?  Satoshi wrote about pruning in section 7 of the design paper, but as far as I know, no pruning solution has been implemented.<p>Why not?  I&#x27;m not crypto-savvy enough or familiar enough with bitcoin to know why you can&#x27;t write a block that rolls up the entire history of the blockchain in such a way that you only need to look at previous blocks if you want to verify the summary block itself.  It would almost literally be just a list of all the addresses and the total amount each one could spend.