This is the context:
The subtle assumption we made is that for every description there is a set of elements that have the objects described. This works most but not all of the time. For example, if I think of the property of red, then I can form the set of all red things. With a description of pink Cadillacs there is a set of pink Cadillacs. But the description “does not contain itself” cannot correspond to a set of things that does not contain itself. This will lead to a contradiction. We must be careful.
What is the meaning of "objects described"?