Word Study
thyself
CIDE DICTIONARY
thyself, pron.
An emphasized form of the personal pronoun of the second person; -- used as a subject commonly with thou; as, thou thyself shalt go; that is, thou shalt go, and no other. It is sometimes used, especially in the predicate, without thou, and in the nominative as well as in the objective case. [1913 Webster]
"Thyself shalt see the act." [1913 Webster]
"Ere I do thee, thou to thyself wast cruel." [1913 Webster]
For further exploring for "thyself" in Webster Dictionary Online