the burning ardour of my soul
Having twice in his letters to his sister (I:L2:5 and I:L3:3) assured her of his prudence, Walton here becomes carried away by his enthusiasm. In terming what impels him a "burning ardour," he utters what is almost a code word in the novel, designating a feature shared by the male protagonists whose value, like the other shared attribute of curiosity, is complexly ambiguous. He has already declared himself overly ardent (I:L1:2). Soon, we will observe the same problem in Victor (I:4:2).