Prayer and the Divine response of Grace, Compassion and Wisdom

When and why does grace answer our prayers or refuse to answer them?  Prayers can issue from the lower nature or the higher in us. Those issuing from lower nature -- ego, desire, heart's attachments, mental ignorance -- may be answered when it will be an aid to our progress and the are refused when it will be an impediment to our progress. At every moment the best possible happens. The best possible depends on our aspiration, receptivity, faith, sincerity, strength, courage, consecration, surrender, etc.