The 12th century saw the apotheosis of pure philosophy and the decline of the Kalam, which later, being attacked by both the philosophers and the orthodox, perished for lack of champions. This supreme exaltation of philosophy may be attributed, in great measure, to Al-Ghazali (1005–1111) among the Persians, and to Judah ha-Levi (1140) among the Jews. It can be argued that the attacks directed against the philosophers by Al-Ghazali in his work, "Tahafut al-Falasifa" (The Incoherence of the Philosophers), not only produced, by reaction, a current favorable to philosophy, but induced the philosophers themselves to profit by his criticism. They thereafter made their theories clearer and their logic closer. The influence of this reaction brought forth the two greatest philosophers that the Islamic Peripatetic school ever produced, namely, Ibn Bajjah (Avempace) and Ibn Rushd (Averroes), both of whom undertook the defense of philosophy.