In "Augmenting Human Intellect: A Conceptual Framework," Doug Engelbart, head of the Augmentation Research Center at Stanford Research Institute, presented a philosophy that favored efficiency over ease-of-use in human-computer interaction, notes Richard Monson-Haefel. In essence, Engelbart felt that basing computer interactions on the most efficient systems was the best way to achieve an optimal human-computer symbiosis. Monson-Haefel thinks the best embodiment of Engelbart's views is his five-finger keyboard, which is designed for use with one hand and carries out very rapid data entry and computer interactions when combined with a computer mouse, which Engelbart also conceived of. The keyboard-mouse combination was very tough to learn, which points to the crux of Engelbart's dilemma: More efficient and potentially more powerful human-computer interfaces have a very steep learning curve. Monson-Haefel says the modern approach to human-computer interaction stresses ease-of-use and usability without training, which runs counter to Engelbart's philosophy, which led to some of the most exceptional computer technologies in use today. The author does not think Engelbart's preference for efficiency is a completely unsound notion, and he reasons that "perhaps, like the violin, people could reach a new level of synergy with computers if they followed Engelbart's philosophy and focused on efficiency over ease-of-use."