Excellent example of an attention to the picturesque that did not fascinate Lupi, judging by the number of paintings he created within the 
genre, but which here has the particularity of presenting two young Angolans, known as Catraio and Mariana, hired by Serpa Pinto to 
accompany him on the their scientific expedition trip to Central Africa, in 1879. 
They played a fundamental role in the completion of this geographical exploration, by highlighting important complicities, described in Serpa Pinto's diary, "Como travessei África", published in 1881. 
The portrait, probably commissioned by Serpa Pinto, was in the author's studio in 1883, when he died.

A certain conflict is present between the abstract, sketchy, neutral-colored background, executed within academic parameters, 
and the colorful costumes, vibrant and foreshadowing an open-air palette that Lupi saw in Paris and admired.  
The fact that this painting is unfinished makes it revealing of the painter's technical procedure.
Thus, on a neutral background, the paint is placed in thick, sponged layers, with a sometimes pure color that establishes complementary 
contrasts, defining the bright areas and leaving the dark and shadowy areas more shapeless and tonal. 
Classical learning from the painting of the Venetian school, and specifically from Titian, was crucial for Lupi.

Pedro Lapa  e  Maria de Aires Silveira