Kant's 'Groundwork'

I have put off reading Kant directly for too long, though of course I am familiar with his ideas.

But, I have been set to read his 'Groundwork of the Metaphysics of Morals'. Of course, one discovery was that by 'metaphysics' he means something like 'rational concepts not empirically derived at all'.

Anyhow, this from him:

Nor could one give worse advice to morality than by wanting to derive it from examples. For, exvery example of it represented to me must itself first be appraised in accordance with principles of morality, as to whether it is alos worthy to serve as an original example, that is, as a model; it can by no means authoritavitively provide the concept of morality. Even the Holy One of the Gospel must first be compared with our ideal of moral perfection before he is cognized as such; even he say of himself: why do you call me (whome you see) good?...But whence have we the concept of God as the highest good? Solely from the idea of moral perection that reason frames a priori and connects inseparabloy with the concept of a free will. Imitation has no place at all in matters of morality, and examples serve only for exnouragement, that is, they put beyond doubt the practicability of what the law commands and make intuitive what the pratcice rule expresses more generally, but they can never justify setting aside thier true original, which lies in reason, and guiding oneself by examples.

Wow, one thing you have to give him is his determination to be consistently rational at all times. But to assert that imitation has no place in morality? My goodness! Also, here we see the old Euthyphro debate about whether God is good or good is God. Is good subject to some concept or law of the good? Or, is he somehow more arbirtrarily sovereign over it, such that what is 'good' may be subject to change or alteration in some way?