The following quote from Aristotle's Metaphysics is utterly baffling to me:

The causes and starting-points of distinct things are distinct in a way, but in a way--if we are speaking universally and analogically--they are all the same...for example, the elements of perceptible bodies are presumably: as form , the hot and, in another way, the cold, which is the lack; and, as matter, what is potentially these directly and intrinsically. And both these and the things composed of them are substances, of which these are the starting-points (that is, anything that comes to be from the hot and the cold that is one [something-or-other] such as flesh or bone), since what comes to be must be distinct from them.

What is the meaning of "lack" here? Also, what is he talking about when he makes a connection between hot and cold on the one hand and blood and bone on the other?

Anyone who can put this into plain english would be helping me immensely. Thanks in advance!

  • 1
    Privation : not having what a being " should" have by nature. ( To be distinguished from mere negation). Dec 20, 2020 at 23:45
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    This is Aristotle's account of change, it is explained more clearly in Physics I.7, see Cohen's notes. Change requires three ingredients: form, its lack and the subject that gains or loses it. When the change is substantial, i.e. a substance is created or destroyed, the subject that undergoes change is matter, pure potentiality that can manifest both form and its lack. And so a piece of bronze is changed into a statue by acquiring form, or flesh and bone acquire "intrinsic heat" when they come to be.
    – Conifold
    Dec 21, 2020 at 6:02

1 Answer 1


"Lack" means "privation". A blind man has a lack or privation of something due to his nature (the ability to see, in this case). Privation differs from negation. A rock is non-seeing (negation) because the ability to see is not part of a rock's nature; one does not say a rock is blind, but non-seeing.

St. Thomas Aquinas's short work On the Principles [or "starting-points"] of Nature ¶8 describes the three principles (matter, privation, and form):

  1. In order that there be generation three things are required: being in potency which is matter, non-existence in act which is privation, and that through which something comes to be in act which is form. For example when a statue made from bronze the bronze which is in potency to the form of the statue is the matter; the shapeless or undisposed something is the privation; and the shape because of which is called a statue is the form. But it is not a substantial form because the bronze, before it receives the shape, has existence in act and its existence does not depend upon that shape; rather it is an accidental form, because all artificial forms are accidental. Art operates only on that which is already constituted in existence by nature.

Describing privation:

  1. Privation differs from the other principles, because the others are principles both in existence and in becoming For in order that a statue come to be, it is necessary that there be bronze and, further, that there be the shape of the statue. Again, when the statue already exists, it is necessary that these two exist. But privation is a principle in becoming and not in existing, because until the statue comes to be it is necessary that it not be a statue. For, if it were, it would not come to be, because whatever comes to be is not, except in successive things, for example in time and motion. But from the fact that the statue already exists, the privation of statue is not there, because affirmation and negation are not found together, and neither are privation and habitus. Likewise, privation is a per accidens principle, as was explained above, but the other two are per se principles.

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