 To know oneself does not mean to have a perfect science of what a soul is. Philo knows all the suppositions elaborated by philosophers and he uses many of them, but without ever saying that he is in possession of knowledge of the soul. It has been rightly said that his purpose was not to build a scientific but a “religious psychology”. In this kind of psychology, it was not essential to know if a soul has seven components besides reason, as it is said by the Stoics, or three, like in the Platonic division, or if it contains, besides reason, nutritive and sensitive parts like in Aristotelianism. Here I’ll give a few examples of his varieties of uses. In Opif. 117, soul is compared to a puppet show, the seven puppets being manipulated by the hègemonikon, the central rational element. This metaphor strongly reminds us of the Stoic comparison with the octopus, but is also very different from this image. The octopus is a living unity, while the puppet master is essentially different from his puppets. The Stoic metaphor of the octopus is a monist one, but the Philonian image, inspired from Plato (Laws 644d), is strongly dualistic. The puppets are not even irrational beings as they are mere objects. But it is true that in Leg. 1.28, the image of the source and the stream could have been used by the most orthodox of the Stoics if separated from its context. In 1.29, Philo says that the intellect (nous, note that he does not use the Stoic word logos) is like a source going to the senses. There is, however, no contradiction in all this. In 1.30, Philo uses a strictly Stoic definition: the living being is characterized by representation and impulse. But when he arrives to the human being at 1.31, Stoicism is completed by a Biblical quotation (Genesis 2:7). A Stoic image is a good way to speak about living beings, but it is not enough when the narrative is about humans. That is why Philo often uses the distinction between rational and irrational beings with an opposition between the hègemonikon, unique and rational, and the other parts of soul, divided in seven and irrational. However, it must be added that in Philo, dualistic images do not imply the division of the soul. In Leg. 2.8, he asserts that sensation and passions are like parts and products of a unified soul. Such are the multi-layered levels of language Philo is capable of using at every page. For him, it is impossible to know what a human soul is, but it is not necessary to have this kind of knowledge in order to try to understand what the meaning of the word of the Lord is. To be conscious of her ignorance in the field of psychology, far from being an obstacle, actually helps to have a better perception of the limitations inherent to human nature. But this consciousness itself necessarily rises from the confrontation of the philosophical doctrines.