Each of the attitude scales constitutes an axis in a multi-dimensional space. In effect, given our total so far of 39 scales, we have a 39-dimensional space. At any given time, our emotions and attitudes are represented by a point in this 39-dimensional space, with the intensity indicators serving as coordinates along each dimension. A complete attitudinal inventory, should one decide to express it, would consist of reading off each of the scale values for each of the emotions, with the vector sum serving as a distinct single point, which is our attitude.
Now no one is going to ever utter a string of 100-odd attitudinals to express their emotions. If asked, we normally do not recognize more than one or two emotions at a time – usually the ones that are strongest or which most recently changed in some significant way. But the scale system provides some useful insights into a possible theory of emotion (which might be testable using Lojban), and incidentally explains how Lojbanists express compound emotions when they do recognize them.
The existence of 39 scales highlights the complexity of emotion. We also aren't bound to the 39. There are modifiers described in Section 13.6 that multiply the set of scales by an order of magnitude. You can also have mixed feelings on a scale, which might be expressed by cu'i , but could also be expressed by using both the “positive” and “negative” scale emotions at once. One expression of “fortitude” might be .ii.iinai - fear coupled with security.
Uttering one or more attitudinals to express an emotion reflects several things. We will tend to utter emotions in their immediate order of importance to us. We feel several emotions at once, and our expression reflects these emotions simultaneously, although their order of importance to us is also revealing – of our attitude towards our attitude, so to speak. There is little analysis necessary; for those emotions you feel, you express them; the “vector sum” naturally expresses the result. This is vital to their nature as attitudinals – if you had to stop and think about them, or to worry about grammar, they wouldn't be emotions but rationalizations.
People have proposed that attitudinals be expressed as bridi just like everything else; but emotions aren't logical or analytical – saying “I'm awed” is not the same as saying “Wow!!!” . The Lojban system is intended to give the effects of an analytical system without the thought involved. Thus, you can simply feel in Lojban.
A nice feature of this design is that you can be simple or complex, and the system works the same way. The most immediate benefit is in learning. You only need to learn a couple of the scale words and a couple of attitude words, and you're ready to express your emotions Lojbanically. As you learn more, you can express your emotions more thoroughly and more precisely, but even a limited vocabulary offers a broad range of expression.