οἱ τοῖς πέλας ἐπιβουλεύοντες, λανθάνουσι πολλὰκις ὑφ' ἑτέρων τοῦτ' αὐτὸ πάσχοντες → when people plot against their neighbours, they fall victim to the same sort of plot themselves
nōlens: entis, Part., from nolo.
nōlēns, tis, part. pr. de nolo.