I happened to read the sentences : "However great may be the importance of the gyroscope as a practical instrument of navigation or engineering, it is not needed as an excuse to demonstrate the importance of theoretical mechanics. The very existence of the general principles of mechanics is their justification."(Lanczos C. , The variational principles of mechanics, p. vii)
I can't understand the real meaning of the first sentence. Is "However..., it is not needed as an excuse..." a reguliar collocation?