The core of the article presents a systematic survey of Avicenna's empirical epistemology on the basis of his texts (for related subjects also discussed see the table of contents below). The human rational soul, upon its first creation, is absolutely potential, a tabula rasa. As the child grows up, experience (mušāhada) provides him with information about the sensibles through the senses (hiss), from which he abstracts (tajrīd) intelligible concepts, and about himself and the operations of his soul through reflection (i'tibār). The natural operation of his mind (fitra) sorts out the concepts so developed and classifies and orders them according to notions of whether they are particular or general, essential or accidental; it invests them with mutual relations like those of affirmation and negation; and then combines them to form definitions and primary and self-evident propositions which constitute the logical and mathematical framework of thinking. Once these primary notions (awwaliyyāt) are acquired at the stage Avicenna calls dispositional intellect (al-'aql bi-l-malaka), and with further input from the senses, both external and internal, the intellect acquires other intelligibles through syllogistic thinking and the discovery of middle terms (hads), attaining the stages of actual and acquired intellect (al-'aql bi-l-fi'l , al-mustafād). With the help of the empirical datum of one's existence and then the realization of the existence of existence as such, the intellect is able to establish the existence of the necessary existent and of the immaterial substance of his self. In all these operations the function of the intellect is procedural; in itself it has no innate or a priori contents. The texts where Avicenna presents these theories are compared throughout with parallel passages from the work of John Locke, which show a striking similarity to them. The article concludes with a terminological study on the terms tajrīd, tajriba, mušāhada, and ma'nā as used by Avicenna.