Thomas Jefferson makes use of the phrase "follow truth" a number of times in his writings.
When advising his fifteen-year-old nephew Peter Carr, Jefferson encouraged the lad to "follow truth, justice, and plain-dealing":
If ever you find yourself environed with difficulties and perplexing circumstances, out of which you are at a loss how to extricate yourself, do what is right, and be assured that that will extricate you the best out of the worst situations. Tho' you cannot see when you fetch one step, what will be the next, yet follow truth, justice, and plain-dealing, and never fear their leading you out of the labyrinth in the easiest manner possible.1
Late in life, Jefferson described his own youthful self as "never fearing to follow truth":
[T]hey [common-place books] were written at a time of life when I was bold in the pursuit of knolege, never fearing to follow truth and reason to whatever results they led, & bearding every authority which stood in their way.2
Upon reading "the voluminous letters of Cicero," Jefferson shared his thoughts on good government with John Adams, citing the necessity to "follow truth as the only safe guide":
[T]heir minds were to be informed, by education, what is right & what wrong, to be encoraged in habits of virtue, & deterred from those of vice by the dread of punishments, proportioned indeed, but irremissible; in all cases to follow truth as the only safe guide, & to eschew error which bewilder us in one false consequence after another in endless succession. these are the inculcations necessary to render the people a sure basis for the structure of order & good government, but this would have been an operation of a generation or two at least, within which period would have succeeded many Neros and Commoduses, who could have quashed the whole process.3
Describing the university under construction in Charlottesville, Jefferson assured English historian William Roscoe that the university's founders were "not afraid to follow truth":
[T]his institution will be based on the illimitable freedom of the human mind. for here we are not afraid to follow truth wherever it may lead, nor to tolerate any error so long as reason is left free to combat it.4
1. Jefferson to Carr, August 19, 1785, in PTJ, 8:406. Transcription available at Founders Online.
2. Jefferson to Dr. Thomas Cooper, February 10, 1814, in PTJ:RS, 7:191. Transcription available at Founders Online.