Nowhere have I found an indication of Portocarrero's birth-date. He became Bishop of Calahorra in 1587, and was translated to Córdoba in 1594; he died on September 20, 1600.
Alonso Getino (op. cit., p. 48) writes, however: 'la Canción del conocimiento de sí mismo, que es la primera cuya fecha se puede averiguar, la escribió diez años después de entrar en religión'. This is an inference from the closing lines of the poem:
aunque sané del mal y su accidente
diez años há que soy convaleciente.
In a note to the passage quoted above, Alonso Getino refers to the Canción al nacimiento de la hija del Marqués de Alcañices, written, as he thinks, 'en un tono impropio de un imberbe'. He appears to have no doubt as to the authenticity of this composition: the correctness of the ascription of this poem to Luis de Leon is at least questionable.
The pieces printed by Sanchez are translations of Ode X, Book II; Ode XXII, Book I; Ode XIII, Book IV; and Epode II.