Non possumus

It originated with the martyrdom of the Martyrs of Abitinae, who were murdered in AD 304 when Roman Emperor Diocletian prohibited Christians under penalty of death to possess the Sacred Scriptures, convene on Sunday to celebrate the Holy Eucharist, and erect premises for their assemblies.

The phrase was not intended to express incapacity but, on the contrary, absolute moral determination to obey the Catholic Faith.

The full sentence of the phrase is "sine dominico non possumus" ("we cannot [live] without Sunday").

[2] The phrase has been vivid throughout the life of the Church, being used by pontiffs also in troubled times such as when Pope Pius VII was arrested by the French troops of Napoleon who had again invaded the Papal States in 1809.

Offered various forms of compromises in exchange for his freedom, he said to his captors: "Non debemus, non possumus, non volumus" (we must not, we cannot, we will not") and accepted his exile first to Savona and then to France until 1814.