No, Mark Carney isn't recycling Seinfeld or buying hydro plants.

Mark Carney has used the phrase "We are masters in our own home." in the current tariff war with the United States, and people have thought he's either copying Seinfeld's "Master of my domain" from an episode about who could go the longest without masturbating, or Quebec Premier Jean Lesage's campaign slogan, Maîtres chez nous, for his successful 1962 election bid that had to do with buying more hydro plants for Hydro-Quebec. It's not. It's really from the poem 'Our Lady of the Snow', which had the unique subtitle "(Canadian Preferential Tariff, 1897)", probably one of the few poems that do refer to tariffs, written by this guy:

Rudyard Kipling, 1895, via Wikimedia

Kipling was an Imperialist and white supremacist, and he admired Canada for setting its own tariffs. After a long trade war with the USA (One that was amped up by hefty tariffs imposed on Canadian goods by Trump idol President William McKinley) the 1897 National Policy gave reduced tariffs to UK imports.

The poem repeats "Daughter am I in my mother’s house,/ But mistress in my own."  , something that Sir Wilfrid Laurier quoted when talking about Canada's place in the British Empire, and follows with "Soberly under the White Man’s law/My white men go their ways.", something Laurier and Carney omitted!

The title of the poem likely comes from Notre-Dame-des-Neiges (Our Lady of the Snows), which is the largest cemetery in Canada, which shares the summit of Mount Royal in Montreal with Mount Royal Cemetery, largely Protestant, and two Jewish cemeteries. 

It is named after the legend that a wealthy couple in 4th century Rome asked the Virgin Mary for a sign for what to do with their wealth and there was a snow fall in August on  Esquiline Hill, where the couple built Saint Mary Major, now a Papal basilica where Pope Francis has been laid to rest.  The title of the poem might have been an allusion to Laurier being only the second Catholic Prime Minister of Canada and the first French-Canadian to hold the position.