 Aristotle begins the investigation with the most familiar and widely recognized case, which is the form or essence present in sublunary matter-form compounds. It is announced in Z.3 (1029b3–12), but not begun until some chapters later and not really completed until the end of Θ.5. And by then it is with actuality (entelecheia) or activity (energeia) that form is identified, and matter with potentiality. The science of being qua being can legitimately focus on form, or actuality, then, as the factor common to all substances, and so to all the beings. But unless it can be shown that there is some explanatory connection between the forms of all these substances, the non-fragmentary nature of being itself will still not have been established, and the pictures given to us by the various sciences will, so to speak, be separate pictures, and the being they collectively portray, divided.