This article aims to give an overview of the use and the meaning of images in two types of school textbooks used in Spain from the early twentieth century until the end of the 1960s: the textbooks "Lecciones de cosas" ("object lessons") and those used for the teaching of religion. For this analysis the iconographic-iconological method will be used as it is applied in the study of art history. In this way it will be seen how it is possible to arrive at didactic and pedagogic conclusions that can help to understand the intentionality of the school textbooks as they were used in the process of teaching and learning. The goal is to show that the illustrations used did not merely aim to transmit information and facts; rather, the artistic code chosen played a fundamental role in transmitting ideas and teachings of a far broader scope. It will also be seen how the illustrations differ not only in the contents that they were meant to transmit, which is to be expected, but in the didactic use that was made of them and, more importantly, in the behaviour and attitudes that they strove to encourage in the students who studied them. It is proposed to contrast the way in which these textbooks used images to teach about the world around us with the way they attempted to show another "world", one not normally perceptible to children's senses. The article will also delve into the question of how illustrations translated this paradox between this life and the "other life", establishing differences and similarities in the way such content and teachings were transmitted. (Contains 15 figures and 79 footnotes.)