So I'm guessing you want this to say something like 'nothing is impossible for the brave' or something like that? Because that's what it means. It's not bad Greek, and correct by verse rules. If it was prose you'd at least want ἐστι on the end, and you'd probably want to replace τοῖς θαρροῦσιν with ὑπὸ τῶν θαρρῶν. An alternative suggestion though, this time actually found in the Classical corpus, if an obscure text admittedly, is οὐδὲν ἀνάλωτον ἀρετῇ which means 'nothing is unassailable to bravery' from *Rev.Phil.1.70* which seems to be an obscure late Greek tragedy. Anyway, your Greek is perfectly fine, as long as that's what you want it to mean.


>from Rev.Phil.1.70 which seems to be an obscure late Greek tragedy. Would that it were! The phrase appears in a discourse by Choricius, a rhetorician of the 6th AD century. The passage is cited in the LSJ (s.v. ἀνάλωτος) from the 1877 issue of the French periodical [*Revue de Philologie*](https://books.google.com/books?id=eDC7lkcbYH4C&pg=PA55) (vol. 1, p. 70, hence *Rev. Phil.* 1.70). This was apparently the only place where that discourse was published in full until the 1929 Teubner edition. By the way, the original phrase is also attested, in Plutarch ([Alexander, 58](https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A2008.01.0129%3Achapter%3D58%3Asection%3D1)): >οὐδὲν ᾤετο τοῖς θαρροῦσιν ἀνάλωτον οὐδὲ ὀχυρὸν εἶναι τοῖς ἀτόλμοις.


Thank you, very helpful! Unfortunately the online edition of the LSJ doesn't have a list of contractions and works so I couldn't follow that up.


Τοις θαρρουσι is totally fine