Hmm...this is a little bit a problem, because I don't know and haven't read any of such books.
Everything I know up until now, is a combination of reading on several forums, listening and learning from those who already understood lot of things about this reality, and of course - personal experience and ideas.
I can recommend reading Castaneda, because he is the only one I know (and who is printed in English) who explain about so called Nagual or energy world. And sensing words, is sensing energy of those words.
oltecnagual.com/nagual.htm
The Toltecs look at creation as consisting of the Nagual and the tonal. The Nagual is all that is. It is unstructured. The Nagual condenses and the tonal is formed. The tonal is structured energy. The average person only perceive the tonal. As we move into the world of energy we enter, what is referred to by the Toltecs as the Second Attention.
The Second Attention is the world of energy. As all form comes from energy there are many benefits gained from the ability to negotiate and maneuver in the Second Attention. The Second attention is not bound by space and time. When in the Second Attention we are able to "see" events before they come into manifestation. We can "see" patterns of energy before they manifest into form.
But in my opinion, even if his books are very insightful, most of the people can't use the described technics, simply because they work in a very specific environment (read frequency envelope) that "allow" such things to occur. Also because not all of the seekers wish or should be "warriors". In my opinion, his material can be good "introduction", but the real practice technics or approaches should be developed by the seeker himself, because learning how to feel or "see" energy, is an art and not science. Like a person who wish to learn how to paint: he can know all the available technics, but he won't become an "artist" unless he will feel and know how to access and express his own intuition and imagination. Feel it with a heart and not only by mind.
I can offer several tips, though.
I would recommend to start with sensing energy of "real" people, or words that come from "real" mouths.
Simply because it easier, and because sensing written words is an "extention" of the same idea, also because we already know how to do it, just didn't know that it has a name ;) The key is to learn how to listen to our intuition and use our imagination. To make a whisper of our inner self to sound like a loud and clear voice.
But first some basics.
We are all made of stars! (well, it's a joke ;) ) The fact is, everything in this world have it's frequency. Everyone of us have our own FRV (frequency resonance vibration). And the goal of this forum is help us to rise this FRV. But what doest it mean actually? Cass said that genetics marry with soul if present. Development of our higher self depends on development of a soul. And body provides it's own lessons and progression on a short cycle, adding broader properties to something that can be called "frequency profile" or FRV. By developing ourselfs, we broaden our awareness and perception. And we do it by creating new thought pathways with something we call outside reality. Imagine a vast and most complicated neuron net. Each person have a specific portion of neuron connection on this net. Those who have higher awareness, have more connections, allowing them to percept and "see" something that is "far away" from others. With each new or additional connection, soul increases it's own potential, therefore can not only to perceive but also DO (infuence). This kind of FRV profile carry more "weight", and sometimes can "bend" the reality around it. Here take a look at this transcript:
Perception is bonded by awareness. Others are bonded to their awareness of you and all else.
Q: (V) Well, while this was happening to me, was this also happening to others in my general area?
A: No. Not likely. You do not yet realize how rare higher awareness is.
Q: (JN) What triggered it?
A: Frequency envelope thinning due to patterning imprint repetition of Violette in her environment.
Q: (V) Alright what's a frequency envelope you brainy types. (R) Actually, frequency envelope, [asking
Ark] isn't that what we were doing with the wave generating computer program? (A) Frequency envelope is
something like that.
A: Your awareness maintains a frequency emanation in concert with those in your environment. When there
are fluctuations in bonding frequencies both between you and your environment, and the frequency bonding
of another, the fluctuations create discontinuities.
We all have our own FRV (our connections) but we all part of the vast system called 3d reality, therefore there are connections where our profiles intercept and allow us to experience common reality. So when we learn to think outside of the box, we actually learning how to rearrange our connections with this reality and to grow a new ones. And such change create an immidiate dissonance in the System. So it tries to return to status quo, to low a growing potential because it's creating a turbulence, effecting other connections. And sometimes it can result in a curios effect I call "thinking out loud". People around us (or those who are connected to us through "thought net", those who resonate with us) get a similar ideas to ours, or even can suddenly tell something that just went through our mind. It's also can effect electronic devices like computers, especially if the turbulence was created by conficting thoughts.
(R) Okay, that makes sense. (L) It does? (V) Okay then tell me. (R) Okay. It's like resonance. If the
environment has a particular frequency...hmm... (V) We were asking about the frequency envelope and
what it is. (R) And it's Violette. And violet is high energy, right? The color spectrum right? [The group
reviews the previous C's answer...] (R) Exactly, so it's a quantum jump. GROUP: Yeah. (R) Because you're
at one level and unless something strange happens that's where you're at. (L) In other words--you
emanate energy, the other person emanates energy, and the energy exchange is between you and the
environment, and between you and the person and the environment, and your environment is maintained,
and the envelope of energy is maintained around you. But if there is...what? Fluctuations? (R) Ah! "Your
awareness maintains a frequency emanation in concert with those in your environment." Hence, if your
environment has a frequency that allows for a higher frequency, I mean, it always has the lower, but in
some cases it can allow for higher. (L) They're talking about it being fluctuations in the environment. If
somebody or something in you're environment is... (A) But the question is--which properties of environment
that we can describe in terms of...(L) Well they're saying that the fluctuations are in Violette. (R) In
concert with the environment. (L) And in concert with people who are in the environment. In other words,
something is breaking up and you are no longer frequency bonded to the people in the environment in the
same way; there is a fluctuation there. What is it called when you add too much energy to something? It
becomes unstable. Your reality construct is unstable. That's what I would say. (R) You have a bigger
marble that you can fit in a bigger hole if the hole happens to be there. (L) Right.
A: Rejoice! You are growing out of your shoes.
So when we interact with people, we interact with their perception, with their connections to outer reality.
Those who resonate with us, have similar frequency - create a comfortable feelings, those who are very different, create discomfort. And by different I do not mean "interests, hobbies or points of view, but energy potentials and their thoughts. Most of the people do not understand the source of this discomfort. They may be even feel it on a subconscious level, but it will effect their thoughts and subtle attitude toward a person in question. For example, an OP will feel a subtle aggression toward a "souled" one, especially if it's "awaken".
They will lie to themselfs or even won't be aware, but their energy will carry the message nevertheless. And this message will be "imprinted" on them. And it is possible to feel it, or to "smell" it. Maybe you'll find it funny, but thoughts "smell" :) It also possible to feel sudden aggression toward some person without any reason. Those thoughts can be analysed, and if there is no basis from you "side", you perceive what he (on subconscious level) thinks of you or about the one he is talking about.
There is a french animated movie "Time masters". I highly recommend it. In this film, there were two funny empathic creatures who could hear or "smell" the thoughts.
And they were saying about one of the evil characters that his thoughts stinked. Well, we can't read thoughts, but we still can smell them. :) We just need to listen to our intuition and use our imagination. And also here, is all about a first impression. Our natural tendency is to ignore our gut feeling and relay too much on actual words that come out from a persons mouth, or his attitude or cloth. It can be all a big lie. What can't be a big lie, is his frequency and smell emination of his thoughts. So what we need to do, is to catch this first impression, hold it, extend it and then analyze it.
Make a little exersise at work or at any other place you meet or talk to people.
Next time you talk to a person, try to understand what kind of feeling he gives you. What kind of energy eminating from him. Imagine that everyone have an energy cacoon around them, and when those cacoons meet or intercept, it's possible to feel the other person. Imagine that you touch his energy with invisible hand. Examine your thoughts. Try to put your feeling into images or forms. For example: there is a person at my work that everytime he just walking by, I have a need to make a shower. His energy stinks so much, I can barely stand when he opens his mouth. He is very manipulative and a coward. I perceive him as a hyena (it's even insolting to an animal). There are others that sticky like fishes, that maybe don't stink, but you still don't want them to "touch" you. There are those of "vampiric" type, them you can feel in your solar plexus. Even listening to them sucks energy, because attention creates a link. There is also another vampiric type, more sophisticated and mostly aware. They buff the mind of another person using complex words, creating a so called raport, then feed on the energy. This leak can be sensed in a throat area. But not everyone so black and negative. There are wonderful people who give a soft and warm feeling, like breeze. There are also those that maybe they are not a conscious seekers, but it possible to feel a resonance with them. It's like a connection of a heart, there is no discomfort. But the start is: use your imagination and ignore rationalisation (at first) that based on your prior familiarity with a person. See where it takes you.
Actually, kids and animals are not fooled by appearance. I wont recommend it to try on a strange dog, but you can try it on some familiar kid. Smile at him, but feel anger toward him inside. And observe his face. Maybe at first he will smile back, but quickly he will spot the deception.
Several tips on sensing words.
Everyone of us heard ones some foreign language we are not familiar with. And we always can spot some specific impression this language creates. For exampe, when I first came to Israel and heard Hebrew, I thought that everyone was singing, because this language have soft, wavy flow, like theeey aaaall siiing, up and down, up and down. So the Spanish. On the other hand, Israelis said that Russian sounds like language that contain only curses :) Very strict and dry. German was sound like barking, and Dutch was sound like a language without vowels, only with stop signs. :) And Americans sounded like they have a never-ending chewing gum in their mouth. (please don't be insulted. I just try to make an example of impression).
After we learn the language, we lose this "objective" ability to sense it from outside. So if this is possible, listen to completely foreign language (but without watching a person) and try to feel a meaning, emotion, anything behind it. Just listen to a flow without trying to understand it. It can be done with familial language as well, but foreign is much easier at first.
And then listen to a familiar language, also without watching a person. Use the same imagination as in the case of sensing the energy. When you do, try to imagine the words as the tiny waves of patterns that coming toward you. What kind of structure do they have, color, sound?
In order to "tune into the flow", imagine that your energy is flowing back and forth like a wave, touching the flow of words, mixing with it and bringing it back to you. Feel like it coming back to you and going forth again and again. The same thing can be done with a written word.
It's only so structural at first. Then it's just become additional sense or natural ability. Nothing magical.
Hope it's clear enough...