http://auditdefender.com/credentials/attachment/4/ Blowing in the Wind
[31a middle] Rava: Bundles of leaves that are gathered into one place (and accordingly set aside for use) on YomTov are still prohibited to use. Because, they will likely blow away and get scattered by the wind (and then not be contained in one appropriated area and thereby prohibited).
see T’s lesson: When we gather all our good deeds into one glorious pile, it is easy for us to lose them due to one wind of a bad thought or action. We must control ourselves, and never lose our leaves to the wind.