"To be interesting, ornamentation should represent objects which remind us of poetic ideas".
for an object to be beautiful, "it is necessary that its form contain nothing superfluous, but only the material conditions which make it useful: we must take into account both the material and the use which will be made of it.".
"the most important requirement for an object that is to be considered beautiful is that it fulfill the purpose for which it is destined".
the character of a work of art "the definition of its esthetic-moral condition." Adding that "it is also the criterion for ornamentation which should reveal the form that is dictated solely by the complete satisfaction of some need." .
He felt that public objects should be severe in character, and geometric ornamentation to be preferable, with the use of natural forms from time to time for contrast. As an example of this principle, he cites Greek examples, especially the Erechtheum. .
"Common sense tells us that simple forms are characteristic of magnificence and abundant ornamentation is more properly found in small masses.".
In dealing with the character of churches, Gaudi advises "do not conceal the great masses, but rather, on the contrary, keep their magnitude in mind, dissolving, if necessary, their imposing effect by means of fitting and simple ornamentation.".
The forms of the exterior should mirror the forms of the interior. .
Praises the esthetic and structural advantages of the dome.
Forms expressed simply have more grandeur. Those forms derived from geometry produce greater distinctness and clarity. .
The more perfect the form, the less ornamentation that is necessary. He applies this principle to historical styles, saying that "the forms used by the Egyptians, the Greeks, and the Middle Ages did not require so much decoration as those derived from the Renaissance or the Byzantine." In styles which are not original and have been derived from others, decoration is of great importance.