A Stratified World: Avicenna’s Model of the Sublunary Strata

Avicenna (d. 1037) at the age of twenty-one produces a model of the entire sublunary world in strata, one to which he adheres throughout his career, as is evident in the fact that in most of his major philosophical summae, Avicenna presents a consistent model of the sublunary world. Through a close comparison of these texts, I reconstruct Avicenna's model of the sublunary strata. In this process, I point to a complexity his model exhibits, since unlike the fire that encompasses air entirely, water does not encompass earth from all sides. Rather, his model reflects the actual world in which we find earth raised over and above water in the form of dry elevated land replete with mountains. I contextualize the complicated case of raised land first by surveying a theological interpretation of raised land according to which the raising of earth above water is the work of God and a direct result of God's providential care for life, since terrestrial organisms, rational (land) animals included, require dry land to live and flourish. Avicenna was deeply conversant with the theological interpretation of raised land and mountains, as he was aware of the inadequacy of the scientific theories on the formation of land and mountains that were available to him, as with that of the Brethren of Purity. After providing this theological and scientific context, Avicenna's positive theory of raised land and mountains is presented. I argue that Avicenna derives raised land and mountains from his novel theory of mud and its petrification. I end by showing that the significance of Avicenna's contribution to the science is one that he himself recognizes, attested by the fact that he explicitly situates his own theory of petrification into the theological discourse on raised land.