Ha, I remembered.
It is sensible/sensitive I was thinking of. I don't know if sensitive has changed but sensible used to mean highly emotional and (by current definition) sensitive. The novel in question was, of course "Sense and Sensibility". It has completely reversed it's meaning to rational and not emotionally motivated. I wonder if there was a time when it was halfway inbetween and two people conversing would use the same word with opposite intent.