“Cultivated mind is the guardian genius of Democracy” was in Texas President Mirabeau B. Lamar’s first address to the Texas Congress. The words are the motto of the University of Texas at Austin and appear on the Hall of Noble Words in the Main Building (Texas Tower).
   
 
Wikipedia: Mirabeau B. Lamar
Mirabeau Buonaparte Lamar (August 16, 1798 – December 19, 1859) was the second president of the Republic of Texas, following David G. Burnet (1836 as interim president) and Sam Houston.
 
Lamar was born near Louisville in Jefferson County, Georgia. During his early adult years, he started and ran a successful newspaper in Columbus, Georgia, known as the Columbus Enquirer. Before heading to Texas, he sold his newspaper company, and used the proceeds to finance his trip out west. The paper is still published as a McClatchy publication and is the major daily newspaper of the Columbus area.
   
He moved to Texas in 1835. He joined the Texas Revolutionary army under Gen. Sam Houston as a private in the cavalry after hearing of the massacres at the Alamo and Goliad. On the eve of the Battle of San Jacinto, Lamar made a courageous rescue of two surrounded Texans in a move that drew a salute from the Mexican lines. He was promoted to Col. and was the commander of the cavalry during the battle the following day. His term as President of Texas began in December of 1838 and he served until 1841.   
 
University of Texas Traditions: The UT Seal
University of Texas Traditions: The UT Seal
Jim Nicar, The Texas Exes
(...)
In November 1881, the Board of Regents of the University of Texas convened in Austin for their inaugural meeting. Among the many items on the agenda, a sub-committee of the board was asked to design a seal for the new university. They completed their task in a single afternoon.
 
The original UT seal borrowed liberally from the seal of the State of Texas, with a five pointed star framed on the left by an oak branch, representing strength, and on the right by an olive branch, signifying peace. Placed within a circle, “Universitas Texana” labeled the seal as belonging to the University, with the motto “Non Sine Pulvera Palma.” A well-known Latin phrase, the motto may be translated as “The prize cannot be won without effort,” or in more modern terms, “Do your best.”
 
Money was allocated to create a brass carving, but the University seal wasn’t very popular. It was seen only rarely, limited to decorating degrees and a few other official documents.
 
In 1901, Dr. William Battle, a well-known and popular professor of Greek on the Forty Acres, took it upon himself to design a new, more distinctive seal for the University. He may have been prompted by the regents’ decision in 1900 to recognize orange and white as UT’s official colors, and thought the time was right. Of the original seal, Battle thought, “Except for the word Universitas, it might just as well have been the emblem of the State Penitentiary.”

In his usual thorough way, Battle purchased books on heraldry, sent for and received copies of seals from universities across the U.S. as well as from Oxford and Cambridge in England. At his own expense, Battle hired a leading firm in heraldic design - the Bailey, Banks and Biddle Company of Philidelphia - as consultants and to sketch prototypes according to his directions.

The process went through several versions, all of which are still preserved in the UT archives in the Center for American History. Battle himself changed the motto to Mirabeau Lamar’s famous quote, “A cultivated mind is the guardian genius of democracy,” which at the time regularly appeared on the inside covers of most University publications. Battle’s Latin translation of Lamar was “Mens Instructa Civitatis Custos,” but this sounded a bit clunky. Instead, Battle conferred with friend and colleague Dr. Edwin Fay, head of UT’s Latin Department, who suggested, “Disciplina Praesidium Civitatis.”
 
In its final version, Battle described the University seal:
 
“In conformity with general usage, the design adopts as its central feature the shield form that shows the origin of its heraldic arms. The shield is divided into two fields, the upper white, the lower orange, the University colors. In the lower and larger field are the historic wreath and star of the Great Seal of the State of Texas; in the upper field is an open book, fit symbol of an institution of learning. The shield rests within a circle of blue, the color of sincerity, containing the motto, “Disciplina Praesidium Civitatis.” This is Professor Edwin W. Fay’s rendering of the apothegm of President Mirabeau B. Lamar, “Cultivated mind is the guardian genius of democracy.”
 
“Around the disk of blue is a larger disc of red, color of strength, bearing the words, ‘Sigillum Universitatis Texanae.’”
 
Battle presented his seal to UT President William Prather in 1903. Two years later, on October 31, 1905, the Board of Regents officially approved Battle’s proposal, though the words, “Sigillum Universitatis Texanae,” were changed to English, “Seal of the University of Texas.” Within a year, the new seal appeared on library bookplates, invitations and programs of University events, and, of course, on degrees. 
 
Leadership
Let’s take a look at the seal of the university. It features a Latin version of this statement of Mirabeau B. Lamar, second President of the Republic of Texas: “The cultivated mind is the guardian genius of democracy, and, while guided and controlled by virtue, the noblest attribute of man. It is the only dictator that freemen acknowledge, and the only security which freemen desire.” This statement appears in the Hall of Noble Words in the Main building, also known as the Tower.
   
Google Books
Texas: The Rise, Progress, and Prospects of the Republic of Texas
by William Kennedy
London: R. Hastings
1841
Pg. 327:
“Education is a subject in which every citizen, and especially every parent, feels a deep and lively concern. It is one in which no jarring interests are involved, and no acrimonious political feelings excited; for its benefits are so universal that all parties can cordially untie in advancing it. It is admitted by all, that cultivated mind is the guardian genius of Democracy, and while guided and controlled by virtue, the noblest attribute of man. It is the only dictator that freemen acknowledge, and the only security which freemen desire. The influence of Education in the moral world is like light in the physical; rendering luminous what before was obscure. It opens a wide field for the exercise and improvement of all the faculties of man, and imparts vigour and clearness to those important truths in the science of government, as well as of morals, which would otherwise be lose in the darkness of ignorance. Without its aid, how perilous and insufficient would be the deliberations of a government like ours! How ignoble and useless its legislation for all the purposes of happiness! How fragile and insecure its liberties! War would be conducted without the science necessary to insure success, and its bitterness and calamities would be unrelieved by the ameliorating circumstances which the improved condition of man has imparted to it; and peace would be joyless, because its train would be unattended by that civilisation and refinement which can alone give zest to social and domestic enjoyments.—  And how shall we protect our rights if we do not comprehend them? And can we comprehend them unless we acquire a knowledge of the past and present condition of things, and practise the habit of enlightened reflection? Cultivation is as necessary to the supply of rich intellectual and moral fruits, as are the labours of the husbandman to bring forth the valuable productions of the earth. But it would be superfluous to offer to this Honourable Congress any extended argument to enforce the practical importance of this subject. I feel fully assured (Pg. 328—ed.) that it will, in that liberal spirit of improvement which pervades the social world, lose not the present auspicious opportunity to provide for literary institutions, with a munificence commensurate with our future destinies.”
     
Google Books
The Book of Texas
by Harry Yandell Benedict and John Avery Lomax
Garden City, NY: Doubleday, Page and Co.
1916
Pg. 362:
In an address to the Congress of the Republic two years later President Mirabeau B. Lamar delivered a sentence which has become the motto of the University of Texas and is printed on every piece of literature sent out by the (Pg. 363—ed.) institution: “Cultivated mind is the guardian genius of democracy. ... It is the only dictator that freemen acknowledge and the only security that freemen desire.”
 
Google Books
The Last Linotype:
The Story of Georgia and Its Newspapers Since World War II
by Millard B. Grimes
Macon, GA: Mercer University Press
1985
Pg. 218:
For many years The Enquirer—the newspaper he founded and left behind in Georgia—carried in its masthead each morning the following quotation from his first presidential message to the Texas Congress: “The cultivated mind is the guardian genius of democracy, and while guided and controlled by virtue it is the noblest attribute of man. It is the only dictator that free men acknowledge, and the only security which free men desire.”
 
Google Books
Quote It Completely!
by Eugene C. Gerhart
Buffalo, NY: William S. Hein Publishing
1998
Pg. 259:
A cultivated mind is the guardian genius of democracy, and when guided and controlled by virtue is the noblest attribute of man. It is the only dictator that freemen acknowledge and the only security that freemen desire.
LAMAR, Mirabeau B.,

, Vol. XXXVII, No. 2, April 1965, p. 1.