Canto 3&4

Canto 3
1. "all fear must be left here, and all cowardice die" (pg. 25). Hell is a place where the evil and the suffering feed off of the fear and cowardice. This sign serves as a warning to Dante that he shouldn't become involved in what the condemned souls are feeling. If he doesn't leave his fear at the entrance of Hell, then his soul might get sucked into the suffering and he could become trapped forever.
2. "cursing the human race, God and their parents" (pg. 35). The only people that these souls have the right to blame for their fate is themselves. In the Aeneid, there were many reasons why a person could end up in Hell, such as killing your kin, betraying your country, etc. In this book, we see that one of the ways a person can end up in Hell is by blaming others for a fate that was your own doing.
Canto 4
1. "not trees, but a wood of thronging spirits" (pg. 37). The woods are something that can't be moved because of their roots in the place where they are planted. The only way to make an entire forest move would ultimately cause the destruction of the woods. You would have to chop down the trees and transport them as smaller pieces, but this would also kill them. These souls also can't be moved because they are rooted in the place where fate has put them.
2. "and far more honor: that fair company then made me one among them" (pg. 39). It makes Dante feel like one of the heroes of old to be considered one of a group of such great writers. This makes him more confident about his ability to pass through Hell unharmed. He feels especially honored to be linked with Virgil in his journey through the depths of Hell, and he believes this is why he is gifted with the presence of these great poets.