The Jews as Representative of the World

In his introduction to his commentary on Isaiah (published around 1846), Joseph Alexander writes, 

"If the Jews could have been made to understand or to remember that their national pre-eminence was representative, not original; symbolical, not real; provisional, not perpetual; it could never have betrayed them into hatred or contempt of other nations, but would rather have cherished an enlarged and catholic spirit, as it did in the most enlightened; an effect which may be clearly traced in the writings of Moses, David, and Isaiah....(The Mosaic dispensation) was scrupulously faithful even to the temporary institutions of the ancient Church; but while it looked upon them as obligatory, it did not look upon them as perpetual.  It obeyed the present requisitions of Jehovah, but still looked forward to something better.  Hence the failure to account, on any other supposition, for the seeming contradictions of the Old Testament, in reference to the ceremonies of the Law.  If worthless, why were they so conscientiously observed by the best and wisest men?  If intrinsically valuable, why are they disparaged and almost repudiated by the same men?  Simply because they were neither worthless nor intrinsically valuable, but appointed temporary signs of something to be otherwise revealed thereafter; so that it was equally impious and foolish to reject them altogether with the skeptic, and to rest in them for ever with the formalist." - Alexander, Commentary on Isaiah, p52.