Full Idea
The problem of 'temporary intrinsics' is that in one model we think of properties as relations to times (I am 'bent' relative to now), but change sometime involves intrinsic properties. I am just plain bent, not bent with respect to something else.
Gist of Idea
Properties cannot be relations to times, if there are temporary properties which are intrinsic
Source
report of David Lewis (On the Plurality of Worlds [1986], p.202-4) by Theodore Sider - Four Dimensionalism
Book Reference
Sider,Theodore: 'Four Dimensionalism' [OUP 2003], p.95
A Reaction
[I've compressed Sider's summary] The question of whether intrinsic properties endure over time runs in parallel with the question of whether objects endure over time, and the two issues cannot be separated.