Does the Spirit retrograde or “involve”?

No, Spirit never retrogrades. It always goes forward, sometimes it stops, but it never goes back. If it returns to appearance, as in the case where it no longer fits into the moral evolution of a population and will incarnate in another, more backward civilization, it is because it has not yet advanced morally, in fact.

God creates us simple and ignorant. During the first steps of our evolution, we have no conscience, but only instinct, which is from the Law of God and, therefore, is good by definition. The lion that kills the zebra does not do evil, but good, for he is responding to instinct.

Further on, when we enter the realm of consciousness, we conquer free will, that is, the ability to choose. With it, we start to TRY and, from the attempt, mistakes and successes are born. The one who errs trying, is not doing evil, but good, because he is following the laws of God. Evil consists only when the individual starts to err by will, thus cultivating imperfections. When creating an imperfection, the Spirit will suffer on account of it, for more or less time, until it realizes the harm it does to itself, repents and honestly wants to overcome this imperfection, through atonement.

That is why, in Kardec's works, more than once the Spirits used the expression "will be doubly punished": it does not mean that God will punish him more or less - because God does not punish - but that, after acquiring an imperfection , the Spirit will spend a lot of time trying to get rid of it.