 In contrasting the Forms with the perceptible realm, Plato discusses properties. For example, for all sensible items, A is tall relative to some B and short relative to some C. There is no such thing as anything’s being tall simpliciter. When we call something tall, we measure it against something else, look at it from a particular perspective, and so on. As we might say, “tall” and “short” are relative predicates. But perhaps many more, or indeed all, predicates work that way, even where this is less obvious. Plato’s arguments lead to the question of whether it is conceivable that all our predications are, in this particular sense, relative. If this were the case, it might quite fundamentally upset our conception of the world as furnished with objects that have properties. Such considerations lead to another idea about properties in the perceptual realm. If a fence is low and high, a cloud is bright and dark, a vase beautiful and ugly, and so on, then it seems that, perhaps quite generally, perceptual things are F and not-F. Only the Form of F is F (for example, only the Beautiful is beautiful). While the relevant passages are difficult to interpret, it is clear enough which line of thought comes to influence later skeptics. The skeptics engage with the idea that, if something appears to be F and not-F, it is not really (or: by nature) either F or not-F.