diff --git a/ch10.asciidoc b/ch10.asciidoc
index d091e5d7..dd676fb6 100644
--- a/ch10.asciidoc
+++ b/ch10.asciidoc
@@ -86,7 +86,8 @@ new block, containing transactions that occurred since the last block,
 is "mined" every 10 minutes on average, thereby adding those
 transactions to the blockchain. Transactions that become part of a block
 and added to the blockchain are considered "confirmed," which allows the
-new owners of bitcoin to spend the bitcoin they received in those
+new owners of bitcoin to know that irrevocable effort was expended
+securing the bitcoin they received in those
 transactions.
 
 ((("fees", "mining rewards")))((("mining and consensus", "mining rewards