προσκτᾶσθαι
From LSJ
ἔνδον σκάπτε, ἔνδον ἡ πηγή τοῦ ἀγαθοῦ καί ἀεί ἀναβλύειν δυναμένη, ἐάν ἀεί σκάπτῃς → Dig within. Within is the wellspring of Good; and it is always ready to bubble up, if you just dig. | Look within. Within is the fountain of the good, and it will ever bubble up, if thou wilt ever dig.
Greek > English (Woodhouse Verbs Reversed)
(see also προσκτάομαι): acquire in addition, gain in addition, get in addition, obtain in addition
Lexicon Thucydideum
insuper comparare, ditioni suae adiicere, to acquire besides, add to one's dominion, 3.28.3, 4.95.2, 6.18.2, 6.24.3,
PASS. 2.62.3.