# Class Equality is Symmetric

## Theorem

Let $A$ and $B$ be classes.

Let $=$ denote class equality.

Then:

$A = B \implies B = A$

## Proof

This page is beyond the scope of ZFC, and should not be used in anything other than the theory in which it resides.

$\forall x: \left({ x \in A \iff x \in B }\right) \implies \forall x: \left({ x \in B \iff x \in A }\right)$