'Itself' in the Bible

The Spirit itself beareth witness with our spirit, that we are the children of God:

Because the creature itself also shall be delivered from the bondage of corruption into the glorious liberty of the children of God.

Likewise the Spirit also helpeth our infirmities: for we know not what we should pray for as we ought: but the Spirit itself maketh intercession for us with groanings which cannot be uttered.

I know, and am persuaded by the Lord Jesus, that there is nothing unclean of itself: but to him that esteemeth any thing to be unclean, to him it is unclean.