A surgical instrument can comprise a first drive system for advancing a knife bar between a first position and a second position in order to close a jaw, an a second drive system for advancing the knife bar between the second position and a third position. The instrument can comprise a lock engaged with a drive shaft in order to prevent the drive shaft from being advanced. The instrument can further comprise an electrical input and, a switch and an end effector wherein, a tissue - grasping portion can comprise a plurality of teeth, of an electrically non - conductive material. The instrument for supplying energy to tissue can comprise an electrode, and an insulator positioned adjacent to the electrode, insulator comprising a top surface movable relative to the top surface of the electrode. The instrument can comprise at least one steam path within the electrode, configured to vent steam generated when the tissue is heated.