what is victors big fear in delaying his trip

In London, Clerval occupies himself with visits to learned and illustrious men; Victor cannot join him, however, as he is too absorbed in the completion of his odious task. He reflects that the trip would have given him indescribable pleasure while he was still a student; now, however, he wants only to be alone, as "an insurmountable barrier has been placed between [him] and [his] fellow men."