What do the rays mean spiritually?

Each soul is a ray of divinity—

An unquenchable ray, which is capable of radiating eternally, but that ray is like a seed planted in the soil. It must follow the law of its evolution.

It must disintegrate and permit the living principle to develop sufficiently, to uplift its earthly covering and permit its appearance in the sun.

Even then it needs the soft rain and the warm, life-giving sun to bring it to maturity.

It has always to struggle against the encroaching weeds, but it always follows its destiny and struggles to blossom and perfect itself in fruit or flower.

Even when it drops again to earth and decays, it liberates its vital part and comes again to life in another form.

So, each individual soul is brought to maturity through difficulties.