In that treatise, it is not too much to say, Milton had shaken hands again with the old Republican party.
In the preface to it he had dwelt fondly on his former connexion with them, on his recollection especially of the speeches he had heard from some of them in the old Councils of State of the Commonwealth, when he had first the honour to sit there as Latin Secretary, and listen to their private debates.

What clearness then, what decisiveness, in such men as Vane and Bradshaw, on that "important article of Christianity," the necessary distinctness of the Civil from the Religious! Ah! could those old days be back! He had written as if those days had not been satisfactory, as if the dispersion of his old masters of those days had been necessary; but, in so writing, had he not been too hasty?
So he had been asking himself of late; and though, as Richard's Latin Secretary, and writing under his Protectorate, he had not said a word against the established Protectoral Government, he had expressed generally his conviction that England would never be right till either those charged with the Government should be men "discerning between Civil and Religious" or none but such should be charged with the Government.

Now, however, in May 1659, he might speak more plainly.

Richard's Government had been swept away;--Richard's Parliament, which he had addressed, was no more in being; and, by a revolution which he had not expected, and in which he had taken no part, the pure Republic, with the relics of the Parliament that had first created it, was again the established order.

All round about him the men he respected most were exulting in the change, and calling it a revival of "the Good Old Cause." Without pronouncing on the change in all its aspects, he could join in the exultation for a special reason.