ɪnðɪ ɪlˈɛvənθ sˈɛntʃɚɹi, ˈævaɪsənə ɐɡɹˈiːd wɪð ðɪs nˈoʊʃən, stˈeɪɾɪŋ ðætðə hˈɑːɹt pɹədˈuːst bɹˈɛθ, ðə "vˈaɪɾəl pˈaʊɚ ɔːɹ ɪnnˈeɪt hˈiːt" wɪðˌɪn ðə bˈɑːdi, ɪn hɪz kˈænən ʌv mˈɛdəsən.
In the 11th century, Avicenna agreed with this notion, stating that the heart produced breath, the "vital power or innate heat" within the body, in his Canon of Medicine.