Common misconceptions regarding the ocular movements are here combated, especially the fixing of attention chiefly on the particular muscles. Attendant ambylopia is regarded as the cause and not the effect of squint. A consequence of convergent strabismus is limitation of lateral movement. The operative treatment should be limited to advancement and resection. Tenotomy should be avoided. Divergent strabismus is treated in conformity to the same principles. For vertical strabismus, vigorous advancement is advised and tenotomy of an inferior rectus never done. Insufficiency of convergence needs advancement of the interni, and paralytic strabismus often demands advancement.