Almeida is noted for his popularisation of the experimental sciences through his ten-volume Recreação Filosófica ou Diálogo sobre a Filosofia Natural ("Philosophical Recreation, or, a Dialogue on Natural Philosophy", published 1751–1799), written "not for those who are educated in deep learning, but for those that, by lack of books written in their mother tongue, live without instruction".

He shared a concern about the melancholia of the Pre-Romantics with others like the Marquise of Alorna or Bocage, but his optimism derived from the knowledge gained from reason and religion.

While in France, he settled in Bayonne, and chose Ambroise de Lombez as his spiritual director, subscribing to his brand of piety based on interior resignation and confidence in God's grace.

[4] He delivered the controversial inaugural address at the Academy's first formal session, on 4 July 1780, in which he compared the country's backwardness in scientific matters to that of the Kingdom of Morocco.

[5] Like the rest of the Portuguese elites, Almeida was horrified by the worst excesses of the French Revolution, and spent his final years as a vocal champion of Portugal's Christian heritage against atheism and the errors of a society based on the political philosophy of Jean-Jacques Rousseau.