Two types of object (substantival) clauses are closely connected in construction with final clauses.
1. Object clauses after verbs of effort.
2. Object clauses after verbs of fearing.
Both stand in apposition to a demonstrative expressed or implied.
οὐδένα δεῖ τοῦτο μηχανᾶσθαι, ὅπως ἀποφεύξεται πᾶν ποιῶν θάνατον no man ought to contrive (this) how he shall escape death at any cost A. 39a, μηχανᾶσθαι ὅκως τὸ σῶμα . . . κομιεῖ
to contrive how he might bring home the body 2.121 γ, αὐτὸ τοῦτο φοβοῦμαι, μὴ . . . οὐ δυνηθῶ δηλῶσαι περὶ τῶν πρᾱγμάτων I am afraid of this very thing, namely, that I may not be able to make the case plain 41.2, ἐφοβεῖτο . . . μὴ οὐ δύναιτο . . . ἐξελθεῖν
he was afraid that he could not escape A. 3.1.12.