After we realize the consciousness of life, the law of life, peace, and death, we can know the spirit by the sense of the spirit.
The divine life is contained in the Holy Spirit. According to Romans 8:2 the Holy Spirit is the Spirit of life.
When we were regenerated, the Holy Spirit mingled Himself with our spirit (Rom. 8:16; 1 Cor. 6:17).
The divine life is mentioned in Romans 8:2, which refers to the law of the Spirit of life. Eventually, the divine life becomes the life not only of the Holy Spirit but also of our spirit, because now the Holy Spirit in whom the divine life is contained mingles Himself with our spirit. These two spirits have become one, so the divine life is the life of both of the two spirits, the Holy Spirit and our spirit.
We can know the spirit by the inner sense of the spirit. The divine life in the Holy Spirit through our spirit gives us the sense of freshness, liveliness, strengthening, brightness, holiness, reality, satisfaction, etc.
By the sense of life, we can know the spirit. When we sense all the above items deep within, that is the sense of life, and this sense proves that we are walking according to the spirit (Rom. 8:4).