Sentence:  Thus, when he drew up instructions in lawyer language...; his clerks, however, understood him very well. If he had written a <WSD>love letter</WSD>, or a farce, or a "ballade", or a story, no one, either clerks, or friends, or compositors, would have understood anything but a word here and a word there. For his signature, however, that was different. 
Meaning of the word marked with <WSD> tags:  A letter written about the author's love for the intended reader.