Final answer:
Masaccio's Holy Trinity, often confused with El Greco's work, shows God the Father, Сhrist on the cross, and the Holy Spirit, together with witnesses and donors, and a vanitas symbol.
Step-by-step explanation:
The artwork commonly referred to as El Greco's Holy Trinity is not to be confused with Masaccio's Holy Trinity. The question seems to merge attributes of different artworks, which can lead to confusion. To clarify, Masaccio's Holy Trinity, a seminal work for the use of linear perspective, is placed in a church setting rather than a completely celestial one. It illustrates a powerful and protective God the Father with a cruciform halo receiving His resurrected Son, and the Holy Spirit depicted as a white dove in the center. The figure of Сhrist reveals His suffering through the wounds and expression of his crucifixion. Beside the main scene, the νirgin Mary and Saint John are present as witnesses. The artwork also includes the figures of donors and a vanitas symbol, represented by the skeleton, reminding viewers of their mortality.