[Footnote 103: Metaphys. [Greek: D]. p. 1021, a. 26, b. 3; also I. p. 1056, b. 34. Bonitz in his note (p. 262) remarks that the distinction here drawn by Aristotle is not tenable; and I agree with him that it is not. But it coincides with what Aristotle asserts in other words in the Categoriæ; viz., that to be _simul naturâ_ is not true of _all_ Relata, but only of the greater part of them; that [Greek: to\ ai)sthêto\n] is [Greek: pro/teron tê=s ai)sthê/seôs], and [Greek: to\ e)pistêto\n pro/teron tê=s e)pistê/mês] (Categor. p. 7, b. 23; p. 8, a. 10). As I have mentioned before (p. 71 n.), Simplikius, in the Scholia (p. 65, b. 14), points out that Aristotle has not been careful here to observe his own precept of selecting [Greek: oi)kei/ôs] the correlative term. He ought to have stated the potential as correlating with the potential, the actual with the actual. If he had done this, the [Greek: sunu/parxis tô=n pro/s ti] would have been seen to be true in all cases. Eudorus noticed a similar inadvertence of Aristotle in the case of [Greek: pte/ron] and [Greek: pterôto/n] (Schol. 63, a. 43). See 'Plato and the Other Companions of Sokrates,' vol. ii. p. 330, note x. I transcribe a curious passage of Leibnitz, bearing on the same question:--"On réplique maintenant, que la vérité du mouvement est indépendante de l'observation: et qu'un vaisseau peut avancer, sans que celui qui est dedans s'en aperçoive. Je réponds, que le mouvement est indépendant de l'observation: mais qu'il _n'est point indépendant de l'observabilité_. Il n'y a point de mouvement, quand il n'y a point de changement _observable_. Et même quand il n'y a point de changement observable, il n'y a point de changement du tout. Le contraire est fondé sur la supposition d'un Espace réel absolu, que j'ai réfuté demonstrativement par le principe du besoin d'une Raison suffisante des choses." (Correspondence with Clarke, p. 770. Erdmann's edition.)]