. - 
THE BELFAST ADDRESS. 457 
for the expression of opinion, the doctrine of " twofold 
truth" was invented, according to which an opinion might 
be held " theologically," and the opposite opinion " philo- 
sophically." * Thus, in the thirteenth century, the creation 
of the world in six days, and the unchangeableness of the 
individual soul, which had been so distinctly affirmed by 
St. Thomas Aquinas, were both denied philosophically, but 
admitted to be true as articles of the Catholic faith. When 
Protagoras uttered the maxim which brought upon him so 
much vituperation, that "opposite assertions are equally 
true," he simply meant to affirm men's differences to be so 
great, that what was subjectively true to the one might be 
subjectively untrue to the other. The great Sophist never 
meant to play fast and loose with the truth by saying that 
one of two opposite assertions, made by the same individual, 
could possibly escape being a lie. It was not "sophistry," 
but the dread of theologic vengeance, that generated this 
double dealing with conviction; and it is astonishing to 
notice what lengths were allowed to men who were adroit 
in the use of artifices of this kind. 
Toward the close of the stationary period a word-wea_ri- 
ness, if I may so express it, took more and more possession 
of men's minds. Christendom had become sick of the 
School Philosophy and its verbal wastes, which led to no 
issue, but left the intellect in everlasting haze. Here and 
there was heard the voice of one impatiently crying in the 
wilderness, "Not unto Aristotle, not unto subtle hypoth- 
esis, not unto church, Bible, or blind tradition, must we 
turn for a knowledge of the universe, but to the direct 
investigation of nature by observation and experiment." 
In 1543 the epoch-marking work of Copernicus on the 
paths of the heavenly bodies appeared. The total crash of 
Aristotle's closed universe, with the earth at its center, 
followed as a consequence, and "The earth moves!" be- 
came a kind of watchword among intellectual freemen. 
Copernicus was canon of the church of Frauenburg in the 
diocese of Ermeland. For three-and-thirty years he had 
withdrawn himself from the world, and devoted himself to 
the consolidation of his great scheme of the solar system. 
He made its blocks eternal; and even to those who feared 
it, and desired its overthrow, it was so obviously strong, 
* "Lange," 2nd ed. pp. 181, 182. 
