William Penn, as a theologian, wrote books. William Penn, as a Christian philanthropist and statesman, did a work which surpassed his books. “How happy must be a community instituted on their principles,” said Peter the Great, speaking of the Quakers. “Beautiful,” cried Frederic the Great; “it is perfect, if it can endure.” It has endured. [Sidenote: QUAKERS.--BARCLAY.] Robert Barclay, a Scotch Friend, the son of Colonel David Barclay, of an ancient family, and of Catherine Gordon, of the ducal house of that name, published his famous _Apology_ in 1676, two years after Penn had published _The Christian a Quaker_. With nothing like the flowing style of his English contemporary, he had a more robust understanding, a keener conception of what he meant to say, a still more logical method of treatment, and, without any show of learning, perhaps he had a deeper amount of scholarship, obtained during his education and residence in France. Barclay affords the student a great advantage wanting in Penn; whereas, in the case of Penn, we have to search through several treatises, extending to five volumes, in order to ascertain the beliefs which he inculcated, in Barclay they are brought together in their proper relation and proportions, and are compactly yet fully expressed. A remarkable coincidence of opinion appears between the two writers, although the intimacy between them does not seem to have commenced until after Barclay had written his _Apology_. He strikes the same key-note as does his friend. The inward light is the true foundation of knowledge, and the Scriptures are not to be esteemed the principal ground of truth and knowledge, the primary rule of faith and manners. He maintains that there is universal redemption by Christ, and that the saving spiritual light enlighteneth every man. Christ is in all men a supernatural light or seed, beyond reason, above conscience, _Vehiculum Dei_: yet there is a great difference between Christ in the wicked, and Christ in the saints. He is quenched and crucified in the one; He is cherished and obeyed in the other.[507] [Sidenote: QUAKERS.--BARCLAY.]