Milk or Solids?

We are going through 1 Corinthians in our church, and last week we were in chapter 3, where Paul says:

Brothers and sisters, I could not address you as spiritual but as worldly— mere infants in Christ. I gave you milk, not solid food, for you were not yet ready for it. Indeed, you are still not ready. You are still worldly. For since there is jealousy and quarreling among you, are you not worldly?

I have been pondering over what Paul means by
milk and solid food. Some commentaries were not very helpful on this issue, but I found Anthony Thiselton's NIGTC commentary and Calvin's to be the most helpful.

The question I was musing over is whether 1 Corinthians only contains "the milk of the Word," which must be supplemented by the solid food in other New Testament books. But what teachings are not found in 1 Corinthians? I suppose you could argue that Ephesians and Colossians have some exalted teaching, not found there, but when Paul says throughout all his writings that the message is Christ, there seems to be a danger that you could think that we can leave behind the simple teaching about Jesus for something deeper, suitable only for spiritual Christians.

But Calvin says

Here it is asked, whether Paul transformed
Christ to suit the diversity of his hearers. I answer, that this refers to the manner and form of his instructions, rather than to the substance of the doctrine. For Christ is at once milk to babes, and strong meat to those that are of full age,the same truth of the gospel is administered to both, but so as to suit their capacity.

Fee, Thiselton and Garland seem to agree with this interpretation, and it satisfies this little black duck!