الثَّابِتُ ثَابِتٌ
What is established is established.
If subject and predicate are understood in precisely the same respect, no additional claim is communicated. In “the realities of things are established,” however, the speaker is defending a contested thesis: the objects of cognition have realities not dependent on subjective preference.
The difference lies in the respect in which a statement is made. A repeated definition may be empty; affirming the reality of something whose status is contested can be informative.
A claim must be interpreted through its purpose and logical context, not solely through superficial repetition of words.