Anima Astrologiae or A Guide for Astrologers by William Lilly 1676

The 40th is, To consider if an Infortune, whether he be Significator or not, be Peregrine; that is, not in any of his Dignities, for then his malice is increases; but when in his Dignity it somewhat abates it; that is in his House, Exaltation, or Terms; but in his Triplicity or Face very Little, and in Hayz least of all.

41.Whether an Infortune be Significator