CELESIA, PAOLO. — Biologist and thinker, b. in Genoa on 3 Apr. 1876, d. in Rome on 12 June 1916. After graduating in natural sciences, he founded and directed for five years (1899–1903) the *Rivista di scienze biologiche*, with a positivist orientation. A spiritual crisis led him back in 1902 to the faith in which he had been raised, and he sought to know its rational foundation through a thorough study of St. Thomas and the most notable exponents of Catholic thought.
C. was a convinced finalist, and since the strongest opponent of final causes in the architecture of the universe was Kant, his greatest concern was to refute Kant’s conclusions after having thoroughly examined his doctrine. In 1913 he translated Kant’s work of 1763, *Der einzig mögliche Beweisgrund zu einer Demonstration des Daseins Gottes*, the first Italian translation, which remained unpublished until 1923; while from 1910 to 1914, in various observations and notes on Kant’s critique of teleological judgment, he combated what in Kantianism is contrary to the fundamental positions of Christian spiritualism.
Since the true difficulty of the teleological proof does not lie in the credibility of supernatural ends that justify the objective reality of natural ends, but rather in demonstrating their correctness in each case, especially in the face of the existence of imperfection and evil, C. addressed the problem and resolved it by affirming the subordination of the lower to the higher, of the non-living to the living, of the plant to the soul, of the soul to man, and of carnal man to spiritual man, who alone in eternal beatitude will fully attain his end. This argument is treated by C. in the volume *Dalla natura a Dio, attraverso il sacrificio*, consisting of various notes composed between 1906 and 1916. For him, sacrifice is the general norm of cosmic life, and nature appears as chaos unless irradiated by the law of sacrifice.
The last philosophical volume aims to demonstrate God as the source of the moral law and thus as the supreme distributor of rewards and punishments to men according to their moral behavior, which is imputable to them insofar as they possess free will. None of the most well-known and effective objections against free will is neglected: God’s prescience, various cases of psychic inhibition, scientific determinism, and supernatural grace.
C. left thousands of unpublished folders. This material, entrusted for coordination and publication to Prof. F. Raffaele for the philosophical series and to N. Turchi for the scientific series, was published in Rome. The philosophical series includes: *Studi biologici* (1923), already edited by C. himself in scientific journals; *Appunti di cosmografia e astronomia* (1927), edited by F. Porro; *Nuovi studi biologici* (2 vols., 1932–33). The philosophical series includes: *La teologia, concetto e valore* (1923); *Biologia e finalismo* (1924); *Saggi di filosofia finalistica* (2 vols., 1925–27); *Dalla natura a Dio, attraverso il sacrificio* (1927); *Studi kantiani* (1923), fifth in the series but first in publication date; *Appunti per una storia delle cause finali nella filosofia moderna* (1926); *Libertà e determinismo* (1930).