Hard sentences are good because they cause our intuition to falter.
Daniel Kahnemann divides our mental processing into ‘System 1’ and ‘System 2’; System 1 is that intuitive aspect of our thinking that allows you to read the phrase ‘nut sack’ and instantaneously conjure up a whole series of images, associated words and emotional responses. System 2 is the more rational, conscious part of you that stops you from blurting it out at the planetarium, or all the time.
Easy sentences don’t tax System 2 – we experience ‘cognitive ease’ and System 1 un-reflexively assimilates the data. If a menu is written in a clear font, we’re more likely to make a more intuitive judgement than if we experience even a slightly jarring discomfort upon reading. In the latter case, the cognitive ease is disrupted and System 2 steps in to sort it out. Rational factors like price and calorie content will hold more sway. Meaning, like a font, can also be clear or obscure.
A hard sentence is one that is dense. A sentence with difficult words in it is not difficult to someone who knows the words but downright unintelligible to someone who doesn’t. A dense sentence, on the other hand, is always hard to read. A quick scan doesn’t deliver anything. Stop, read it again, slower.
We are forced to unpack the sentence, engage in a little dialectical effort, break it down and build it back up. When we do build it back up, we consciously reconstruct the process of sentence-forming that the writer engaged in when she wrote it. We replicate their effort. The sentence not only communicates information, it communicates understanding.
Painters have often talked about slowing the eye down; they want us to look at the painting for as long as they looked at it while making it. Hard sentences slow the mind down and make us think about it for as long as the author took to write it.