A descriptive example of one type of Frith:
This divination was made to ascertain the position and condition of the absent and the lost, and was applied to man and beast. The augury was made on the first Monday of the quarter and immediately before sunrise. The augurer, fasting, and with bare feet, bare head, and closed eyes, went to the doorstep and placed a hand on each jamb. Mentally beseeching the God of the unseen to show him his quest and to grant him his augury, the augurer opened his eyes and looked steadfastly straight in front of him. From the nature and position of the objects within his sight, he drew his conclusions.
The 'frith' of the Celt is akin to the 'frett' of the Norseman. Probably the surnames Freer, Frere, are modifications of 'frithir'. Persons bearing this name claim that their progenitors were astrologers to the kings of Scotland.