 Aquinas uses a variety of terms to talk about knowledge, including scientia, cognitio and notitia. Often he seems to use these terms interchangeably, and he shows no interest in trying to define anything like knowledge in its loose and popular sense. He is, however, very much interested in articulating what it would be to have an ideal grasp of some subject, and he refers to such a thing, speaking strictly, as scientia. This is what both the theologian and the philosopher seek, which is to say that this is what Aquinas himself seeks. Each of these fields, theology and philosophy, can be described as a single complex scientia—that is, as a science. We can also refer to the myriad individual conclusions obtained in these fields as scientiae—that is, as items of scientific knowledge. Philosophy itself, moreover, can be divided into various discrete fields of science: logic, physics, astronomy, biology, metaphysics, ethics, and so on. Until the seventeenth century the physical sciences were understood to be contained, in this way, within the field of philosophy. Accordingly, the domains of scientia, conceived most widely, were philosophy and theology.