A method for operating a thread stitching machine for processing printed sheets to form book blocks includes providing at least one sewing station with an active connection to at least one stitching saddle and providing the at least one stitching saddle with an active connection to at least one transporting system. The printed sheets are supplied to the at least one stitching saddle, using the at least one transporting system, in at least one of a substantially vertical and a substantially horizontal plane relative to the at least one stitching saddle. At least the printed sheets in the substantially vertical plane are supplied directly onto the at least one stitching saddle or to a region of the at least one stitching saddle. The printed sheets are supplied to the at least one sewing station resting astride the at least one stitching saddle.