Introduction.

1. Original Arabic texts — II. The Latin translations — III. The treatise "de intellectu" on the intellect — IV. The treatise "de somno et uisione" on sleep and vision — V. The treatise "de quinque essentiis" on the five essences — VI. The "liber introductorius in artem logicae demonstrationis" introductory book on the art of logical demonstration — VII. The manuscript tradition and the present edition.

I.

The four following treatises, which have remained unedited until now, are attributed to the Arab philosopher Ya‘qub ben Isḥāq al-Kindī, 1 who lived in the ninth century AD. The first three are stated to be written by him, while the last is listed as a book composed by his student Muḥammad.

We have sufficient reasons to consider both writings, "de intellectu" and "de somno et uisione," as authentic.

First, the titles of these works are found in the lists of Al-Kindi's works handed down to us by Muḥammad ben Isḥāq al-Nadīm, Ibn al-Qifṭi, and Ibn Abi Uṣaibi‘a. The title of the work "de intellectu" reads: 2

1) Source references in my note: Sulle opere di Ja‘qūb ben Isḥāq al-Kindī in the Rendiconti della R. Accademia dei Lincei. Vol. IV, fascicle 3, 1895. A second (concluding) note will appear soon.

2) Ibid., p. 8, no. 20 (Al-Nadīm no. 22, Qifṭi no. 15, I. a. Uṣaibi‘a no. 20). Casiri, B. I, p. 353: de intellectus essentia on the essence of the intellect. Flügel, Alkindi, p. 21: Treatise on the essence of reason and its clear development.