In this area, which is doubly delimited by a stone wall and a hedge, Andrés Gayoso intended to develop a conceptual idea whose full significance escapes us today. He had two vessels built in stone--a warship and a fishing boat--and a figure, the lord of the serpent, as an intermediary between the two worlds: the calm waters of the upper lake, known today as that "of the virtues" and the turbulent waters of the lower lake known as that "of the vanities".
The location of these artificial lakes, at a diagonal to the longitudinal axis of the main palace corridor, may seem odd to the inattentive observer, yet it is a logical solution based on two conditioning factors: on the one hand, use of the waters of the river Boo, which crosses Oca's orchard (the current lakes were built on the site of a former water mill and the related lake, which we know from the will of Doña María de Neira already existed at least by 1594); and on the other, the location of the chapel towers, with which it is aligned. The choice of the chapel as an axis is no chance matter, and should be taken into consideration when interpreting the meaning of the lakes.
The works carried out on this area, which are fairly well documented in the Medinaceli Ducal Archives (Oca section), began in the second decade of the seventeen hundreds and dragged on for at least fifteen years. During this period the former lake of the old mill was replaced by two lakes with stone masonry separated by a bank and the water mill was moved from its original site (quite possibly the landing stage of the "lake of the vanities") to the top end of the lake of the virtues. The box plantations surrounding the lakes must date at least from this period, which makes them at least three hundred years old.
The series of works described, which continued without interruption, the next starting no sooner was the previous one complete, indicates a preconceived plan. What is more, the concern conveyed by the works contracts over the symbolic representations of the stone figures--"well shaped and carved stones of artillery [...] about to shoot"; "two lions [...] their blazons projecting"--and over the effects of the water when falling ("whose water is to spout from the mouth of the said serpent [...] must fall into a round five-palm basin") unmistakeably denote the intention to develop a very precise message.
It seems evident--or at least that is the most plausible hypothesis--that the 1st Marquis of San Miguel das Penas intended to represent the lakes as an inverted boat (instead of surrounding the ship, the waters fill it) navigated by two smaller boats , forming a symbolic and polysemous contrast between earth and hell, and the vanity of this world (represented by the lower warship) and paradise (symbolised by the upper fishing boat), presided over by the chapel, which appears to float among the vegetation.
As clear as this interpretation may seem, it omits many elements that would need to be incorporated into a more detailed explanation. For example, it does not take into account the heraldic monsters that adorn the warship, or the battlements and spheres (cannon balls) that surround the lakes, or the role played by the gentleman with the serpent, over whose appearance the marquis took special care, as can be deduced from the contract which specifies: "[...] a giant of the size and structure nine palms high and everything else in proportion, with his robes and with his cape and cap, with a sperpent on his shoulder, perfect in every way, which is to serve as a jet and conduct for receiving all the water that flows out of the upper lake into the lower lake, whose water must spout out from the mouth of the said serpent [...]"
This figure clearly alludes to the founding myth of the Neira lineage, as according to Don Servando "they descend from Darío, the great hunter, son of the Wolf Queen, who killed a serpent on the bank of the River Arce, now called Neira, from which they took their name and where they established their family seat".
Since this Wolf Queen is linked by other myths to the apostle St James and to the Christianisation of Galicia, it is not hazardous to guess that the lakes hold a genaeological-religious message that has yet to be deciphered. This idea is further reinforced by the fact that after Andrés Gayoso died, his son Fernando Gayoso y Arias Ozores, without interrupting the work on the lakes, undertook the construction of the current chapel, possibly on the side of the former oratory of María de Neira.