Having now finished his course of philosophy under the discipline of his own brother, Mr. William Blair (who was afterwards minister at Dumbarton). He engaged for some time to be an assistant to an aged schoolmaster at Glasgow, who had above 300 scholars under his instruction, the half of whom were committed to the charge of Mr. Blair. At this time he was called, by the ministry of the famous Mr. Boyd of Trochrigg (then principal of the college of Glasgow), in whose hand, the Lord, as he himself observes[141], did put the key of his heart, so that whenever he heard him in public or private he profited much, being as it were sent to him from God to speak the words of eternal life. Two years after he was admitted in the room of his brother Mr. William, to be regent in the college of Glasgow, though not without the opposition of arch-bishop Law, who had promised that place to another.----But neither the principal nor regents giving place to his motion, Mr. Blair was admitted. After his admission, his elder colleagues, perceiving what great skill and insight he had in humanity, urged him to read the classical authors; whereupon he began and read Plautus, but the Lord, being displeased with that design, diverted him from this, by meeting with Augustine's confession, wherein he inveighs sharply against the education of youth in heathen writings.----Whereupon he betook himself to the reading of the holy scriptures and the ancient fathers, especially Augustine, who had another relish; and though he perceived that our reformed divines were more sound than several of the ancient, yet in his spare hours he resolved to peruse the ancient monuments, wherein he made a considerable progress. In summer 1616, he entered on trials for the ministry, and it was laid upon him to preach in the college-kirk the first Sabbath after his licence; and some years after, being told by some of the hearers (who were better acquainted with religion, than he was then) that in his sermon the Lord did speak to their hearts, which not only surprized him, but also stirred him to follow after the Lord. Upon an evening, the same year, having been engaged with some irreligious company, when he returned to his chamber to his wonted devotion, he was threatened to be deserted of God, had a restless night, and to-morrow resolved on a day of fasting, humiliation and prayer, and towards the end of that day he found access to God with sweet peace, through Jesus Christ, and turned to beware of such company; but running into another extreme of rudeness and incivility to profane persons, he found it was very hard for short-sighted sinners to hold the right and the straight way.