Having executed his commission, Willock returned to Embden; and he quitted Scotland with the less regret, as he left behind him one who was so capable of promoting the cause which he had at heart. When he first arrived in Scotland, Knox found that the friends of the reformed doctrine continued, in general, to attend the popish worship, and even the celebration of mass; principally with the view of avoiding the scandal which they would otherwise incur. Highly disapproving of this practice, he laboured, in his conversation and sermons, to convince them of the great impiety of that part of the popish service, and the criminality of countenancing it by their presence. Doubts being still entertained on the subject by some, a meeting of the protestants in the city was held for the express purpose of discussing the question. Maitland defended the practice with all the ingenuity and learning for which he was distinguished; but his arguments were so satisfactorily answered by Knox, that he yielded the point as indefensible, and {176} agreed, with the rest of his brethren, to abstain for the future from such temporizing conduct. Thus was a formal separation made from the popish church in Scotland, which may be justly regarded as an important step in the Reformation.[260] Erskine of Dun prevailed on Knox to accompany him to his family seat in the shire of Angus, where he continued a month, during which he preached every day. The principal persons in that neighbourhood attended his sermons. After his return to the south of the Forth, he resided at Calder‑house,[261] in West Lothian, the seat of Sir James Sandilands, commonly called Lord St John, because he was chief in Scotland of the religious order of military knights who went by the name of Hospitallers, or Knights of St John. This gentleman, who was now venerable for his grey hairs as well as for his valour, sagacity, and correct morals, had long been a sincere friend to the reformed cause, and had contributed to its preservation in that part of the country.[262] In 1548, he {177} had presented to the parsonage of Calder, John Spottiswood,[263] afterwards the reformed superintendent of Lothian, who had imbibed the protestant doctrines from archbishop Cranmer in England, and who instilled them into the minds of his parishioners, and of the nobility and gentry that frequented the house of his patron.[264] Among those who attended Knox’s sermons at Calder, were three young noblemen, who made a great figure in the public transactions which followed;――Archibald, lord Lorn, who, succeeding to the earldom of Argyle at the most critical period of the Reformation, promoted, with all the ardour of youthful zeal, that cause which his father had espoused in extreme old age;――John, lord Erskine, afterwards earl of Mar, who commanded the important fortress of Edinburgh castle, during the civil war which ensued between the queen‑regent and the protestants, and died regent of Scotland;――and