The eagle and fox attack, drop feathers on, and generally give a hard time to the chariot. The animals, as you might guess, represent a couple enemies of the Church. It’s interesting that there are multiple enemies of the Church, isn’t it? Don’t we usually think of it purely as God vs. the Devil?
For the Church as an institution, the secular side of things generally causes problems. Here, that side is symbolized by the eagle. It was the preferred symbol of the Roman emperors and thus here it represents the Empire. In other words, the “state” side of the Church and the state conflict. When the eagle first swoops down and terrorizes the chariot, the eagle represents the early Roman emperors persecuting Christians. The eagle represents this period. All well and good. But what about when it attacks the chariot a second time and leaves its filthy feathers scattered all over the chariot? Well, according to Dante, the eagle is basically laying claim to the Church. Remember that Dante does indeed want a strong Roman Empire to rule over both the Church and the state. Thus, the feathers represent the “earthly rule, the exclusive prerogative…of the Empire.” In other words, it is signifying the coming of an emperor who will unite the kingdom under the twin pillars of the Church and the state and put everything to rights.
The fox launches his attack on the chariot between the two dive bombs of the eagle. A conventional symbol of trickery, the fox represents heresy. Why might it come between the first and second attacks of the eagle? Well, after the initial persecution of Christianity by the early Roman emperors, Christianity was still a new religion trying to establish its identity. So it comes as no surprise that there were still disbelievers – heretics, we now call them – who challenged the Church. It is telling that Beatrice herself drives the fox away. As a symbol of Divine Knowledge, not only can Beatrice defend herself against all the heretics’ arguments against Christianity, but also anticipate their arguments. So she ousts the upstart fox with little trouble.