A quote from The Scots Kitchen
The potato, like the Gael, travelled to Scotland via Ireland, and crossed by the self-same route. ‘That man has not been dead many years who first introduced from Ireland the culture of the potato into the peninsula of Cantyre; he lived near Campbeltown. From him the city of Glasgow obtained a regular supply for many years; and from him also the natives of the West Highlands and Isles obtained the first plants, from which have been derived those abundant supplies on which the people there now primarily subsist.’2 Its first recorded appearance in Scotland is in 1701, when the Duchess of Buccleugh’s Household Book mentions a peck of potatoes as brought from Edinburgh, and costing half a crown.
‘About (1733),’ Chambers tells us, ‘it was beginning to be cultivated in gardens, but still with a hesitation about its moral character, for no reader of Shakespere requires to be told that some of the more uncontrollable passions of human nature were supposed to be favoured by its use . . . (In 1739) a gentleman styled Robert Graham of Tamrawer, factor on the forfeited estate of Kilsyth, ventured to the heretofore unknown step of planting a field of potatoes.3 His experiment was conducted on a half-acre of ground on the croft of Neil stone, to the north of the town of Kilsyth. It appears that the root was now, and for a good while after, cultivated on lazy-beds. Many persons—amongst whom was the Earl of Perth, who joined in the insurrection of 1745—came from great distances to witness so extraordinary a novelty and inquire into the mode of culture.’
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During the early Celtic period, when adoration was paid to the waters, fish as food was taboo, and even after the introduction of Christianity it continued for a time to be considered dangerous to the purity of the soul.4
I guess we still have a few of these taboos about food. We don't eat horse, dog, or insects because it's considered immoral or dirty.