quidnam homines putarent, si turn occisus esset, cum tu ilium in foro inspectante populo Romano gladio insecutus es negotiumque transegisses, nisi se ille in scalas tabernae librariae coniecisset iisque oppilatis impetum tuum compressisset?

As generally interpreted this line leaves much to be desired because of its unwieldy construction. It is true that est ut plus a form of possum is a common periphrasis in Lucretius . Quite common also is Lucretius' use of the infinitive as a nominative substantive . But the combination of fieri mirarier with the already periphrastic erat ut posset results in ‘a very clumsy phrase.… The line should be regarded as one which Lucretius might have improved on revision’.