Modern man is the child of technology, which is influencing and shaping the progress of all his affairs, But though we be the children of technology, we must be its masters and not its slaves.
The above is a quotation from Julius A. Statton's speech entitled "Science and the process of management" made in New York in 1963.
I have been taught that "though" and "but" cannot occur in the same sentence. But "though / although" and "yet" can occur in the same sentence.
I have seen sentences like the following:
Though he worked hard, he failed in the exams
Though he worked hard, yet he failed in the exams.
He worked hard, but he failed in the exams.
In the given Quotation "though" and "but" occurs in the same clause side by side.
Since Julius A. Stratton was a native speaker I cannot question the grammaticality of his use but I would like to know whether the use is acceptable in modern English.