The moral philosopher, according to Sidney, considers himself to be the superior teacher because of his ability to precisely denotate both vice and virtue and the factors that birth them. Likewise, the historian takes the view that because he is able to go back and use concrete examples from history, these examples make him a far better educator than the philosopher. However, Sidney sees that their are significant disadvantages in both philosophy and history that prevent them from being the best source of education.
He argues that poetry combines the best of both philosophy and history, in that poetry is able to include both example and precept. Using various demonstrations from Homer, he shows the way in which poetry possesses freedom to express the ideal whereas history is bogged down by its need to truthfully represent its subjects, which will inevitably include focus on their vices as well as their virtues. Likewise, poetry is able to present a world where good deeds result in good happenings and where evil is punished, whereas history is limited by the vicissitudes of life, where often evil is rewarded and good punished. Philosophy is not as superior to poetry because it is abstruse and difficult for the common man to understand. Poetry, according to Sidney:
...doth not only show the way, but giveth so sweet prospect into the way as will entice any man to enter into it
The public will listen with great attention to stories of heroes such as Achilles and Hector, and will therefore often be unaware of the didactic purpose of such stories. They will be very unlikely to listen to a philosophical treatise so easily, where the learning is so blatant and pointed.
Lastly, Sidney argues that both philosophy and history are disciplines that derive from poetry, and therefore this shows the natural supremacy of poetry:
So that truly neither philosopher nor historiographer could at the first have entered into the gates of popular judgments, if they had not taken a great passport of poetry, which in all nations at this day, where learning flourisheth not, is plain to be seen; in all which they have some feeling of poetry.
Philosophy and history have only developed as a result of the "great passport of poetry." They both, according to Sidney, have poetry in their origins, and therefore it is wrong to argue that they are supreme to poetry.