E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Læta’re Sunday.
The fourth Sunday in Lent is so called from the first word of the Introit, which is from Isa. lxvi. 10: “Rejoice ye with Jerusalem, and be glad with her all ye that love her.” It is on this day that the pope blesses the Golden Rose.
