The notion is of "stretching" one's mind toward something.
"to direct one's mind or energies," from O.Fr. atendre "to expect, wait for, pay attention," from L. attendere "give heed to," lit. "to stretch toward," from ad- "to" + tendere "stretch" (see tenet).
For St. Thomas, knowing consists neither in receiving an impression nor in producing an image; it is something much more intimate and much more profound. To know is to become; to become the non-I. Does this therefore mean to lose one's being and to be absorbed in things? .... That is certainly not Thomistic intellection. Furthermore, no type of material union or transformation can attain to the degree of union which exists between the knower and the known. If I lost my being in something else, in order to be united with it, I would not become that other being; it and I together would make a composite, a tertium quid, instead of the knower's becoming the known itself. The union of the knower and the known is thus a true and genuine unity; they are more one than matter and form joined together.It seems to me that attention is sort of the linking between the knower and the thing known.... the way that the subject reaches out towards the object of his study. Charlotte Mason says that attention is not a faculty:
Attention is not a faculty at all, though I believe it is worth more than all the so-called faculties put together; this, at any rate, is true, that no talent, no genius, is worth much without the power of attention; and this is the power which makes men or women successful in life. (I talk like a book without scruple, because you know my light is borrowed; Professor Weissall is our luminary.) "Attention is no more than this––the power of giving your mind to what you are about. (Vol 5)This makes it sound like attention is a power (a potentiality) that can be more or less fully actuated by training or at least exercise. It is distinctly human because it is a person's will that inclines him to attend to something, though Charlotte Mason thinks that like all acts of the will it is perfected by habit.