Index your scanned documents.
To install scandex itself
gem install scandex
In order to index files though, scandex relies on imagemagick, ghostscript and tesseract.
brew install imagemagick gs tesseract
To add documents to the index
scandex index ~/Documents/*.pdf
To search for documents
scandex search "Taxes"
To list documents
scandex list
You can also have scandex just watch a directory for incoming new documents
scandex watch ~/Documents/Scanner
By default scandex stores its index in $HOME/.scandex.db but you can use -f PATH to specify where the database should be stored instead.