Despite the wide cross-disciplinary influence of Fra' Luca Pacioli's Summa de Arithmetica, Geometria, Proportioni et Proportionalita (Summa), it has been criticized as being both difficult to read and writ- ten in a mixture of bad Italian and bad Latin; but, paradoxically, intellec- tuals of Pacioli's day praised the style of writing in Summa. Can both viewpoints be correct? The answer to this question is sought by identify- ing what may have inspired Pacioli to write Summa in the manner he did. In doing so, the article considers the times in which he lived and, in par- ticular, the impact that Renaissance Humanism and Humanist Education may have had upon his writing style. The article finds both views were correct in their own timeframes and contexts and that Pacioli's writing style was both an appropriate one with which to address a contemporary merchant society and one which would impress and gain the approval of his fellow humanist educators and patrons.