It is described as the earliest known reference to crop circles, though the stalks were cut and arranged rather than flattened. Every straw, says the 17th-century narrator, was 'placed . . . with that exactness that it would have taken up above an Age for any Man to perform . . in that one night'.
Accompanying a woodcut illustration of the field being mowed with a scythe by the devil is a text relating how it happened. When a farmer asked a neighbour to mow the oats in his 3 1/2 -acre field, the poor man 'endeavour'd to sell the Sweat of his Brows and Marrow of his Bones at as dear a Rate as reasonably he might . . . some sharp Words had passed . . . The irritated farmer with a stern look . . . told the poor man, That the Devil should Mow his Oats before he should have anything to do with them.'
That night, locals saw the farmer's field 'to be all of a Flame, and so continued for some space, to the great consternation of those that beheld it'.
Cereologists noted that the event is recorded as having taken place in August, which tallies with the timing of most modern crop circles. Many of them are discovered in oat fields. But as neither the precise locality nor the farmer's name are specified, a local Hertfordshire historian in 1913 dismissed the story as purely imaginary, a warning 'never to say in anger what might be afterwards a matter for regret'.
Whether the 1678 circle was mowed by the 17th-century's equivalent of the two farmers who in 1991 admitted they had been playing the devil - perpetrating most of the 5,000 crop circles in Britain in the previous 10 years - we will never know.
It is be sold on 2 March, by Woolley & Wallis in Salisbury, Wiltshire.