de forma irrebatible
From LSJ
μελετᾶν οὖν χρὴ τὰ ποιοῦντα τὴν εὐδαιμονίαν, εἴπερ παρούσης μὲν αὐτῆς πάντα ἔχομεν, ἀπούσης δὲ πάντα πράττομεν εἰς τὸ ταύτην ἔχειν → one must practice the things which produce happiness, since if that is present we have everything and if it is absent we do everything in order to have it | so we must exercise ourselves in the things which bring happiness, since, if that be present, we have everything, and, if that be absent, all our actions are directed toward attaining it
