 The universal is at rest in the soul, as it is the ratio common to all those particulars which instantiate it (NLP 33, 504–505). Kilwardby argues that Peter and Paul differ as individuals (they have their own matter and form), but they have something in common—their essence. Universals are, therefore, this agreement (convenientia) in essence. Two human beings agree essentially agreeing in their humanity when that humanity is considered not as individuated in this or that human being, but as abstracted from any concrete individual (QLIIS 17, 71). The universal is one thing (res una) not in the sense of being numerically one (an individual thing) but in the sense of being a unity of agreement or likeness of individual things outside the mind (QLIIS 17, 72).