Invariant theory was at its height in the 19th century with the work of Cayley, Sylvester, Clebsch, Gordan and others. Littlewood claimed that:
Invariant theory ay sa taas nito sa ika-19 siglo sa ang gawain ng Cayley, Sylvester, Clebsch, Gordan at iba pa. Littlewood inaangkin na: