"I have much more to tell you, but you cannot bear it now. But when he comes, the Spirit of truth, he will guide you to all truth. He will not speak on his own, but he will speak what he hears, and will declare to you the things that are coming. He will glorify me, because he will take from what is mine and declare it to you. Everything that the Father has is mine; for this reason I told you that he will take from what is mine and declare it to you. (Jn 16:12-15)
Father has everything. There is nothing in existence which is not of the Father. This is the summary statement about the Father that we find in this passage. Everything belongs to the Father. And the Father is the source of everything. With the same idea we are trying to comprehend the Father.
Father does not hold everything to himself. The Father who is the beginner, the creator, the source of everything shares everything with the son. The other quality of the Father is to share. By sharing everything to the Son, the Son becomes a reflection of the Father. God shares his Divinity and hence The Son also is God. The Father and the Son are equal in everything: one is the other.
The Spirit ‘will take from mine’ and declare to you. The Spirit is a revealer, and all what he reveals is from the Son. And we know that all what the Son has is from the Father. So the Son also shares everything with the Spirit. The Spirit in his turn reveals to the humanity.
The Feast of Trinity makes us reflect on sharing. The Father shares everything with the son and hence the Son and the Father are equal; and the son shares everything with the Spirit and hence they also become equal; thus The Father, the Son and the Spirit are equal to each other in their sharing. All these are shared with us, so that we might become godly people. So sharing makes us godly.