splendid cradle is an expression that is part of the Brazilian National Anthem whose meaning refers to the American continent - more specifically to South America, where Brazil is located - according to the first stanza of the second part of the Anthem:
"Eternally lying in a splendid cradle,
To the sound of the sea and the light of the deep sky,
Fulguras, oh Brazil, flower of America,
Illuminated in the Sun of the New World!"
The author of the Anthem, Joaquim Osório Duque Estrada, makes reference to the country that shines (glows) and is a source of pride, which stands out (flowers) among the other countries that are part of America. The American continent (composed of North America, Central America and South America) was designated the New World as opposed to the Old World (Europe).
According to the lyrics, Brazil will be forever resting in a dazzling place, bathed by the Atlantic Ocean and under the immensity of the sky.
The phrase "Eternally lying in a splendid cradle" has generated some controversy, with some who argue that the word "lying down" expresses the idea of "asleep", "tired", "lazy" or "not fighting", characteristics that would not be representative of the greatness and glory of the Parents.