How is the instrument choosen?

How does the divine Force choose the instrument in which it wants to manifest itself?

Through affinity. For the quality, the nature of the consciousness is visible in the divine domain. It has a special vibration, a special light and this can be perceived. And so, when there is an affinity (sometimes merely an affinity, sometimes an identity, depending on the being’s degree of perfection), the Force goes there. Those who are still in the course of formation but whose psychic being is sufficiently developed are seen, their vibrations are seen, the being that is there is seen and accordingly the degree of manifestation is determined, the exact line of manifestation, the importance and conditions of the manifestation. All that is included in the inner vision.

Ref : Questions and Answers 1953