 As we said above, Avempace presented his Rule of the Solitary (Tadbir al-mutawahhid) as a Regimen sanitatis in order to acquire and preserve spiritual health, which obviously equals to happiness (IB-RS-AP: 11; IB-coll-fakhry: 43; IB-RS-berman: 128). The companion he gave to Ibn al-Imam for his travel, the Epistle of Farewell, was intended to help him attain spiritual happiness. Avempace enumerates the different degrees of pleasure, the highest being science. Man suffers from ignorance and when he reaches the truth, pain goes away and pleasure seizes him. However, intellectual pleasure is also caused by the very fact of knowing.