February 14
Saint Cyril is invoked as patron of ecumenism. Cyril was born Constantine in Thessalonica about 826, the youngest son of an imperial officer (drungarius) of the Byzantine theme of Thessalonica. With his elder brother Methodius he was the architect of the Slavic mission. Sources: https://www.vatican.va/content/john-paul-ii/en/encyclicals/documents/hf_jp-ii_enc_19850602_slavorum-apostoli.html.