The previous verses, and the entire chapter, have glorified the exalted position of knowledge. This verse notes that such a valuable thing takes time and effort to attain.
Kalenatmani – In due course of time
Wisdom is not obtained in a flash. It takes time to sprout, grow, flower, and produce a ripe fruit.
Yoga-samsiddha – Perfection of yoga
Knowledge is the result of patient (kalenatmani) maturation (samsiddha) of karma-yoga. It is not obtained by a rash dash to renunciation (karma-sannyas).
Relation of this verse to text 34
Text 34 explained that one obtains knowledge by submissively inquiring from and serving the wise. This verse, however, states that one obtains knowledge gradually through maturation in karma-yoga. The resolve of the two is that one begins by inquiring from a wise, realized soul. The instructions one receives initiate and guide him on the path of karma-yoga – eventually leading him to perfection in that yoga (yoga-samsiddah), at which point pure knowledge becomes fully realized within his own heart.