Sometimes it will be enoughto have analysed the text mentally : it is not alwaysnecessary to put down in black and white the wholecontents of a document ; in such cases we simplyenter the points of which we intend to make use.But against the ever-present danger oi substitutingone's personal impressions for the text there is onlyone real safeguard ; it should be made an invariablerule never on any account to make an extract froma document, or a partial analysis of it, without