Intercession is where Islam's theory and Islam's practice pull hardest against each other. The theory is direct access: no priest, no mediator, ask God yourself. The practice, across most of Islamic history and most of the Muslim world today, involves asking the Prophet and the friends of God to put in a word — tawassul — at shrines, in poetry, and in the standard blessings. Ibn Taymiyya attacked the practice in the fourteenth century and was jailed over it; the eighteenth-century Wahhabi movement made his position policy, and the demolition of tomb structures at Jannat al-Baqi in Medina on 8 Shawwal 1344 is still commemorated annually by Shia Muslims as a day of mourning. Sources put that demolition in 1925 or 1926. This one doctrine explains more of the internal Sunni conflict of the last century than any other.