From Why Can’t the Impassible God Suffer? Analytic Reflections on Divine Blessedness:

A Cambridge change is a change that an object undergoes in relation to something
else. The object does not undergo an intrinsic change, but merely undergoes an extrinsic
change. For example, as I am currently typing this paper, I am north of the Cambridge
Divinity Faculty. The Divinity Faculty building has the relational property “being south
of Ryan.” Say that tomorrow I take a train down to Cambridge, and stand to the south
of the Divinity Faculty. The Divinity Faculty building has changed relationally with
regards to me, but nothing intrinsic to the building has changed. The building has
merely gone from “being south of Ryan” to “being north of Ryan.” When contemporary
theologians say that the classical God can undergo these sorts of changes, they are
misrepresenting the tradition. Boethius actually gives a similar account of relational, or
Cambridge changes, in The Trinity V. So classical Christian thinkers are aware of the
concept of a Cambridge change, though they do not refer to them under this moniker.
Boethius, like most classical theists, makes it clear that God does not undergo relational
changes. Why? Because, according to Boethius, the category of relation does not apply
to God at all.17 An immutable God, as classically conceived, cannot undergo relational,
or Cambridge changes. In fact, from Augustine to Aquinas and beyond, classical theism
denies that God is really related to creation in order to avoid saying that God undergoes
relational, accidental changes.18 The claim that God is not really related to creation is a
complicated matter. Since I have discussed it at length elsewhere, I shall say no more
about it here.19 What matters for the purposes of this essay is that on classical theism,
God is immutable in that God cannot undergo any kind of change, be it intrinsic or
extrinsic.