John Lyle wrote two Diaries with first-hand descriptions of what he witnessed at Presbyterian Sacramental Meetings now called "camp meetings" during the Second Great awakening. His diaries are especially important because he didn' t like the supernatural events he describes, thus making him an impartial observer. 

Because he was educated in the Scottish Common Sense Realism of John Witherspoon and William Graham, he considered what he saw to be the result of "animal enthusiasm", and not the sovereign work of the Holy Spirit. His Diaries are the most vivid account of supernatural activity in  American history.

Lyle was exposed to Scottish Common Sense Realism by William Graham when he attended Liberty Hall, Virginia. Fortunately, he had an evangelical background before he was taught that salvation is merely a rational process by Graham. He wrote in the family Bible he was "born again August 17th, 1789" in the revival that took place in Virginia at the time.

He was licensed to preach in 1797, and ordained by the Presbyterian Church in 1799. In 1800 he took charge of the Presbyterian churches of Salem and Sugar Ridge, in Clark County, Kentucky, which gave him a first-hand view of the Camp Meetings.

In 1797, he came to Kentucky as a missionary, and in 1800 took charge of Salem church, where he remained for several years. In 1805 he was appointed a missionary within the bounds of the Cumberland Presbytery, and subsequently a commissioner of the Presbyterian General Assembly.

Mr. Lyle subsequently moved to Paris, where he established a female academy, which became one of the most flourishing in the state, embracing from 150 to 200 pupils. In 1809, he declined teaching, but continued in the active discharge of his ministerial labors until 1825, on the 22d of July of which year he departed this life. he intended to destroy His Diaries, since they did not support the verbal restrictive view of the Holy Spirit taught by Presbyterian schools at the time.  

Presbyterian biographies avoid speaking of  his relationship to the events of the Presbyterian Sacramental Meetings described in his Diaries, saying things like, "He bore a prominent part in the trying scenes through which the church was called to pass during the early period of his ministry". They don't mention his Diaries, because what they describe is completely at odds with the salvation view of Scottish Common Sense Realism.

The following true account is from the History of the Presbyterian Church in Kentucky by Reverent Robert Davidson. You can read the entire book here.

Davidson explains how he got the Diary: "The Diaries of the Rev. John Lyle were just on the point of being committed to the flames as waste paper, when they fell into the author's hands, through the friendly agency of the Rev. Robert Stuart. In looking over the contents, which were seen at a glance to be of inestimable importance, the following paragraph came to light".

(Davidson records Lyle's posthumous request, even though it reveals Lyle's fear that his Diary will be used as proof that God works miracles with sinners and saints alike, which would be harmful to the Scottish Common Sense Realism verbal restrictive view of the Holy Spirit). "The foregoing short sketches were written hastily for private use; and should I die before I destroy them, I would not allow my friends to hand them about, or any one to use them, except some judicious friend might make an extract of those few particulars which might be useful in writing a history of the progress of religion in Kentucky."

Davidson justifies his saving the Diary from the fire: "Hereupon the author claimed a warrant for retaining the precious manuscrpt, provided his venerable friend would vouch for his coming under the category of being the "judicious" person required. This Diary, kept during the height of the great revival of 1800-1803, has proved an invaluable document, and will be frequently referred to".

Here is the entire biography of John Lyle from Davidson's History:

The Rev. John Lyle was a native of Rockbridge county, in the Valley of Virginia. His grandfather, who had emigrated from the North of Ireland before the middle of the last century, and his father, were both ruling elders in the Timber Ridge Church.

John Lyle, who was the third of the name in succession, was born October 20th, 1769, and "born again," (according to an entry in the family Bible, in his own handwriting,) August 17th, 1789, in the great revival, when he was nearly twenty years of age. After his conversion he was ardently
desirous of studying for the ministry, but met with no encouragement from his family.

His father was in moderate circumstances, from his determined aversion to employ slave-labor, and designed all that he could spare for the education of the elder son Andrew, who was his favorite, a young man of fine talents and prepossessing figure. John, on the contrary, had been, from his birth, a feeble child, and had received, in his infancy, accidental injuries which affected his appearance; and being very taciturn and reserved, none gave him credit for even ordinary intellect.

His lengthened visage, his ungainly form, and his awkward gait, made him the butt of ridicule in the family, the school, and the neighborhood. His father could not bear the idea of his entering the ministry ; and never spoke of it without bitterness, as destined to disgrace the family by a certain failure. He oflfered to leave him his farm on condition of renouncing his intention: but in case of persistence, he refused to extend the least aid; and true to his word, even after the death of his promising son Andrew, he never gave him so much as a shilling.

John inherited all his father's pertinacity, and resolved to achieve his object by his own exertions. He taught a country school, and thus procured the means of a liberal education at Liberty Hall.

Note: William Graham, the great promoter of Scottish Common Sense Realism was President of Liberty Hall at the time Lyle received his education.

While in college, he was much persecuted by the looser sort of students, who were addicted to gambling, and hated piety; but his courage and firmness at last secured his peace. When Mr. Lyle was licensed, in 1795, his performances far exceeded every one's expectations, and a more favorable estimate was thenceforth entertained of his merits.

After serving as a missionary for a year in his native State, he visited Kentucky in the same capacity in 1797; and in 1800 took charge of Salem Church, where he remained for several years.

Upon the appearance of the bodily exercises in the beginning of the present century, Mr. Lyle was at first at a loss how to regard them; but soon learned to discriminate between the work of God and animal excitement, and exerted himself to check the excesses. He kept a diary during the years 1801, 1802, and 1803, in which he carefully noted all the incidents that occurred at the sacraments and camp-meetings during that period.

This is a truly invaluable document, and, as well as his journal, when one of the Synod's Commission in Green river, has been extremely serviceable m preparing the present history. Mr. Lyle, in consequence of his plain-spoken fidelity, became unpopular to a considerable extent, like others of his brethren.

The first instance of disorder which fell under his notice was on the part of two Methodist preachers from Green river, and poor Lyle was so discomposed that he wandered off into the woods to give vent to his feelings. In his agitation he forgot entirely that he had invited several ministerial brethren to dine with him; and, as he could not be found, they were obliged to sit down to dinner without him.

When preaching at Danville, he was interrupted by sounds resembling the barking of a dog,
produced by two of Houston's deluded parishioners whom he had brought from Paint Lick. Mr. Lyle expressed his desire, in very decided language, that silence should prevail in the house of God; and proceeded without further interruption to conclude his discourse, which was from the text, "Bodily exercise profiteth little." Houston was very angry, and reproached him with having stopped the work of God.

On another occasion, at Paris, he preached a famous sermon from the text, "Let all things be done decently and in order." This discourse gave great offence to some, while others were delighted; and it had a powerful effect in checking the tendencies to disorder.

In 1805, he was appointed by the Synod to ride two months in the bounds of the Cumberland Presbytery, and afterward to sit as one of the Commission on the difficulties of that body. Of this
tour he kept a journal.

Mr. Lyle established a female academy at Paris, which became, under his hands, very flourishing; embracing from one hundred and fifty pupils to nearly double that number. But about1809, the trustees obstinately insisted on discarding the Bible, and all religious instruction; and finding his opposition ineffectual, he withdrew. The school immediately declined, and the number dwindled to little more than a score of pupils.

He died July 22d, 1825, aged fifty-five years, thirty of which had been passed in the ministry.

Mr. Lyle was of moderate talents, not on a par with Campbell, Cameron, or even Mr. Rice; but his sound judgment and his studious habits supplied the lack of more showy qualities. He was in the constant practice of reading the New Testament in the original. He wrote well-digested skeletons of his sermons, though he never carried them into the pulpit. His matter was sensible, and his manner feeling and earnest; but he owed nothing to the graces of elocution. His disposition was naturally
amiable, though he had his weaknesses, and was occasionally betrayed into too passionate warmth. But in the pulpit he possessed, in an uncommon degree, the power of unlocking the founts of feeling, and awakening a sympathetic interest in the bosoms of his auditors.

Even the General Assembly were taken by surprise in 1809, when he defended the Synod in the matter of the Cumberland Presbyterians. Bursting into tears he made a most impassioned appeal, and the Assembly were so affected, that their final judgment was very different from that to which
they had at first inclined. His faithful, earnest, and affectionate style of preaching was very much blessed. On one occasion, at Mount Pleasant, the Rev. William L. McCalla noted the names of thirty-three persons impressed by the sermon, thirtyone of whom afterward became respectable members of the Church. He had a particular tact for benefiting young preachers, whom he delighted to take with him on missionary excursions, and, at times, his conversation would be so heavenly, and his heart so filled with the Spirit of God, that the company felt as if transported to the apostolic days.