Following trails, rummaging through the traces a life has left behind, and making inferences among the clues found as witnesses of history, of a life, of a relationship, of a time, are now common methodological practices for those who study history.

In recent decades, far from the time when biography began to find its place as an approach to history, when it was seen as “history’s poor relative” (^{Holroyd, 2011: 36}), filtering historical processes through the sieve of a single life has become a task strengthened by the punctilious and complex review of historians who seek to retrieve the memory of those who experienced their time in order to analyze the ways and the means through which the subjects dealt with the structural weight of the times in which they lived; how, in spite of the efforts of institutions - and of those who would institute - to discipline, regulate, and limit, at the convenience of political, economic and cultural interests and projects, individuals discover their capacity of agency and negotiate or produce resistances that allow them to express their own voice, and how that voice entails the voices of others, of a collective, how the social is expressed in their bodies. “What is it that leads them to follow the footsteps of another individual, to look into the details of a career?” (^{Arfuch, 2013: 47}).

It is the men, children and youth on foot, the underdogs, who can let us look at the past through their habits, emotions, ways to socialize, confessions, mentalities, and conflicts. They are the subjects of history, and that is why historians are interested in them: that is how they explore the corporality, feelings, practices and silences expressed in increasingly diverse sources, seeking to analyze individual subjectivity and collective processes, as well as social and cultural history. In a biography one may recognize the appropriations of the social mandate, the meanings and interests entailed in discursive practices, and how the tensions among laws, institutions, discourses and regulations that aspired to normalize life are expressed in subjectivity.

Thus, an obsessive, almost detective-like search, leads them to dive into archives, manuscript,¹ rough drafts, letters, documents, portraits, treasured objects, spaces - a house, a desk, a garden, a library - to follow the same paths to look at the same things, to speak to numbers of people in search of their memories, to earn the trust of estate administrators and win over the trickery of testaments (^{Arfuch, 2013: 48}).

Analyzing the careers of those who were students, factory workers, laborers, peasants, teachers, physicians or artists is a complex task because biographies not only contain individual lives but also condense relationships with others and their surroundings in particular historical circumstances and moments.

Last night I dreamed that a revolution broke out.²

I wake up and my mother tells me there are intense political riots. I think about my (premonition?) dream. I have not read the newspapers since the last catastrophe on June 16. Nor have I wanted to hear my classmates’ comments. Why did I dream that dream? I don’t know…

Damn confinement! This is delaying the printing of my book (^{Pizarnik, 2003: 62}).

Summoning singularity is precisely giving ourselves an opportunity to reconstruct the history people have experienced, away from the facts or bombastic events that often make individuals invisible in order to underscore exceptionality. Biography aspires to be an account that will allow us to apprehend social processes in their most complex sense, the links between the singular and the general, social relationships and common desires and projects, to think also about the pains, the fear and the joy. Understanding the feelings of an epoch brings us closer to the analysis of a culture, to producing knowledge from other, more inclusive and complex boundaries where dissent, the negotiations with power in everyday practices, and the difference between being a man, a woman, an elderly person, a child, a peasant, a bureaucrat, a slave, a laborer or a teacher is expressed.

Thus, this issue of Diálogos sobre educación. Temas actuales en investigación educativa presents the dossier “The social biography of teachers: new horizons of knowledge”, with the absolute conviction that analyzing education, its central role in social formation and transformation, the particular projects that the aims of a political and economic system and an idea of nation embodied, necessarily involves understanding those who contributed their bodies, their intelligence, their commitment, their convictions and rejections, the ways in which they expressed them and their specific contributions to public life.

Under the coordination of Guadalupe García Alcaraz and Luciano Oropeza Sandoval - to whom we are deeply grateful for their work - this issue includes articles that help us understand passages from the lives of teachers and stories that not only explain particular social processes but also become places where we can find new ways to recount history, methodological paths and tools that allow us to capture the often elusive subjectivity in the traditional accounts of history. They are “transborder” narratives, as historians often have to reconstruct spaces and moments on which there is no information by using their own imagination in their junctures with research findings.

In fact, resorting to fiction in biographical work is inevitable, insofar as it is impossible to restore the richness and complexity of real life. Not only do biographers have to make use of their imagination to fill in the gaps in documentation and time lapses they find, but also life itself is a continuous interweaving of memory and forgetfulness. Seeking to bring everything to light is therefore at the same time the ambition that guides biographers and an aporia that condemns them to failure (^{Dosse, 2007: 25}).

We can feel the pulse of an epoch by taking a close look at the lives of those who imagined and lived through it. Thus, this issue of Diálogos sobre educación aims to offer our readers new knowledge on the history of education in our region, its particularities and resemblances, and an encounter with the lives experienced by individuals and retrieved by the hard-working researchers of history.