Thomas Jefferson used the phrase "the illimitable freedom of the human mind" at least three times in his writings:

this institution of my native state, the Hobby of my old age, will be based on the illimitable freedom of the human mind, to explore and to expose every subject susceptible of it's contemplation. - Jefferson to Antoine Louis Claude Destutt de Tracy, December 26, 1820[1]

the state in which I live is now engaged in the establishment of an University, in which all the sciences will be cultivated which the circumstances of our country would as yet render useful. this institution will employ the remaining days and faculties of my life, and will be based on the illimitable freedom of the human mind. - Jefferson to Marc Auguste Pictet, December 26, 1820[2]

this institution [the University of Virginia] 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. - Jefferson to William Roscoe, December 27, 1820[3]

 

References

  1. ^ Ford, 10:174. Transcription available at Founders Online.
  2. ^ Coolidge Collection of Thomas Jefferson Manuscripts, Massachusetts Historical Society. Transcription available at Founders Online.
  3. ^ L&B, 15:330. Transcription available at Founders Online.