A problem clearly stated is a problem half solved.
— Dorothea Brande

A problem well stated is a problem half-solved.
Charles Kettering stated quote

And lastly, let us provide in our constitution for its revision at stated periods.
— Thomas Jefferson

A masterpiece is something said once and for all, stated, finished, so that it's there complete in the mind, if only at the back.
— Virginia Woolf

It is often stated that of all the theories proposed in this century, the silliest is quantum theory. In fact, some say that the only thing that quantum theory has going for it is that it is unquestionably correct.
— Michio Kaku