Alexander Grothendieck, Récoltes et Semailles (Reapings and Sowings), from Promenade 9, 1986 (English translation by Roy Lisker)

That is to say that, if there is one thing in Mathematics which (no doubt this has always been so) fascinates me more than anything else, it is neither number, nor magnitude but above all form. And. among the thousand and one faces that form chooses in presenting itself to our attention, the one that has fascinated me more than any other, and continues to fascinate me, is the structure buried within mathematical objects.

One cannot invent the structure of an object. The most we can do is to patiently bring it to the light of day, with humility - in making it known it is discovered. If there is some sort of inventiveness in this work, and if it happens that we find ourselves the maker or indefatigable builder, we aren't in any sense making or building these structures. They hardly waited for us to find them in order to exist, exactly as they are! But it is in order to express, as faithfully as possible, the things that we've been detecting or discovering, to deliver up that reticent structure, which we can only grasp at, perhaps with a language no better than babbling. Thereby are we constantly driven to invent the language most appropriate to express, with increasing refinement, the intimate structure of the mathematical object, and to construct with the help of this language, bit by bit, those theories which claim to give a fair account of what has been apprehended and seen. There is a continual coming and going, uninterrupted, between the apprehension of things, and the means of expressing them, by a language in a constant state [of] improvement, and constantly in a process of recreation, under the pressure of immediate necessity.

As the reader must have realized by now, these theories, constructed out of whole cloth, are nothing less than the stately mansions treated in previous sections: those which we inherit from our predecessors, and those which we are led to build with our own hands, in response to the way things develop. When I refer to inventiveness (or imagination) of the maker and the builder, I am obliged to adjoin to that what really constitures it soul or secret nerve. It does not refer in any way to the arrogance of someone who says This is the way I want things to be! and ask that they attend him at his leisure, the kind of lousy architect who has all of his plans ready made in his head without having scouted the terrain, investigated the possibilities and all that is required.

The sole thing that constitutes the true inventiveness and imagination of the researcher is the quality of his attention as he listens to the voices of things. For nothing in the Universe speaks on its own or reveals itself just because someone is listening to it. And the most beautiful mansion, the one that best reflects the love of the true workman, is not the one that is bigger or higher than all the others. The most beautiful mansion is that which is a faithful reflection of the structure and beauty concealed within things.