Because God is immutable, his wisdom is also unchanging.

[God] is “only wise” perpetually. As the wisdom of man is got by ripeness of age, so it is lost by decay of years; it is got by instruction, and lost by dotage. The perfectest minds, when in the wane, have been darkened with folly: Nebuchadnezzar, that was wise for a man, became as foolish as a brute. But the Ancient of Days is an unchangeable possessor of prudence; his wisdom is a mirror of brightness, without a defacing spot. It was “possessed by him in the beginning of his ways, before his works of old” (Prov. viii. 22), and he can never be dispossessed of it in the end of his works. It is inseparable from him: the being of his Godhead may as soon cease as the beauty of his mind; “with him is wisdom” (Job xii. 13); it is inseparable from him; therefore, as durable as his essence. It is a wisdom infinite, and therefore without increase or decrease in itself. The experience of so many ages in the government of the world hath added nothing to the immensity of it, as the shining of the sun since the creation of the world hath added nothing to the light of that glorious body. As ignorance never darkens his knowledge, so folly never disgraces his prudence. God infatuates men, but neither men nor devils can infatuate God; he is unerringly wise; his counsel doth not vary and flatter; it is not one day one counsel, and another day another, but it stands like an immovable rock, or a mountain of brass. “The counsel of the Lord stands for ever, and the thoughts of his heart to all generations” (Ps. xxxiii. 11).

—Stephen Charnock, The Existence and Attributes of God (Baker Books, 2005), 1:511–512.