The character of the flag, including the allegorical meaning of its colors, is precisely defined by the Texas Flag Code:
(a) The state flag is a rectangle that:
(1) has a width to length ratio of two to three; and
(A) one blue vertical stripe that has a width equal to one-third the length of the flag;
(B) two equal horizontal stripes, the upper stripe white, the lower stripe red, each having a length equal to two-thirds the length of the flag; and
(C) one white, regular five-pointed star:
(i) located in the center of the blue stripe;
(ii) oriented so that one point faces upward; and
(iii) sized so that the diameter of a circle passing through the five points of the star is equal to three-fourths the width of the blue stripe.
(b) The red and blue of the state flag are:
(1) the same colors used in the United States flag;
(2) defined as numbers 193 (red) and 281 (dark blue) of the Pantone Matching System.
(c) The red, white, and blue of the state flag represent, respectively, bravery, purity, and loyalty.
If the U.S. flag and the Texas flag are on the same pole, the U.S. flag is the higher one, but in all other circumstances, the flags are to be of equal height and size, with the U.S. flag raised first and the Texas flag lowered first.
In 1933, the State of Texas also accidentally passed a pledge of allegiance to the Burnet Flag:
Honor the Texas flag of 1836; I pledge allegiance to thee, Texas, one and indivisible.
This was a typo; it was almost certainly supposed to be 1839, not 1836, but it wasn't until 1965 that the error was legally corrected. In 2007, "one state under God" was added after "Texas".
The Lone Star Flag is, I think, one of the better contributions to the heraldry of nations and states: it is neat and clean, easy to reproduce, and easy to recognize.
Public Domain, Link
A Texas Hymn
The birds woke me at the sunrise hour
when grass was dewy and all was pale
beneath the light of a high white star;
it sang the message that all was well.
And I in the breeze (it trickled down
the blades of grass then quickly wound
around my legs to tickle my feet) --
I knew the light, and it was sweet.
The thirsty drink from flowing spring
and come to life, made quick by source;
as I, when I hear mornings sing
in bird, or wind in winding course,
know, as rolling sun will rise,
a Spirit lives, God's very breath,
who lightens sky and human eyes
and raises souls like mine from death.