Chapter 56 cautions us, knowing not speak; speaking not know. The idea that speaking not know should reasonably include thinking. In fact, isn’t speech just giving voice to one’s thoughts? Indeed, thought is a prerequisite for speech. Thus, I feel knowing not think; thinking not know might be a more accurate way to put this. So let’s consider thought first.
Emotion drives thought; thought manipulates emotion 
Seagulls are emotional just like humans. They exhibit anger, fear, need, social bonding, etc. These emotions instigate action in both seagulls and humans. In humans, emotions also instigate and/or influence thought. This is problematic on several levels. Chapter 71 sums up the problem succinctly, Realizing I don’t’ know is better; not knowing this knowing is disease. Any certainty of belief feeds back into our emotions, amplifies them somewhat which then easily initiates over reactions and stress. It can easily be a vicious circle!
Profound Sameness cripples certainty
The following is a more literal translation of the first four lines of chapter 56.
One’s awareness of profound sameness at each flowing moment results in the knowing doesn’t speak. Simultaneously, one’s awareness of differences (i.e., names) naturally results in the speaking doesn’t know. Typically, difference awareness in each flowing moment is a blend of past, present, and future cognitive factors. In contrast, is a ghostly awareness of profound sameness, which by definition is inexplicable, i.e., The name possible to express runs counter to the constant name. When that ‘ghost’ floods awareness, past, present and future can blend into an eternal now, so to speak.
So what am I doing here typing away?
Of course, writing is a form of speech. Therefore, by Taoist definition, I don’t know! Well, that’s not completely true. It is just that knowing doesn’t speak, or rather knowing can’t speak (think, or write). Knowing can’t speak applies to everyone, so we can’t truly discuss it! Anyway, I guess social instinct drives my urge to describe as best I can what I see. Is this an urge to be helpful, to tell my story, call out a warning… or all of these?
In any case, I rely heavily on science to provide a point for reference, a kind of baseline. Sure, science has its problems, but science offers as impartial a view as I’ve found anywhere out there.
Giving how much emotion plays a key role in life, both for seagulls and us, I refer often to need, fear, emotion, and instinct in a broader sense than the meaning for which they are typically associated. These primal states influence perception in general and thought in particular. I’ll address them briefly:
Need and fear: I use the terms need and fear to convey, in the broadest possible sense, the primal biological driving forces of life. Meaning: Feeling need attracts us to what ostensibly facilitates survival; feeling fear repels us from what ostensibly hinders survival. Such need and fear are often below the threshold of thought. They only evoke conscious thoughts once they pass some relative threshold of awareness.
Emotion: I use the term emotion as broadly as possible to differentiate feeling from thinking. This includes all the experiences, conscious or otherwise, that we are unable to adequately describe through language or portray artistically. Chapter 14 may hint at this subtlety… This is called the without of shape form, the without of matter shape.
Instinct: We commonly think instinct pertains mostly to animals. It is their means of making choices in life. We, on the other hand, believe we have free will, and thus are able to operate outside the bounds of instinct. This is more wishful thinking than actuality. In any case, instinct is something innate and along the lines of need, fear, and emotion. Instinct is the biological bedrock upon which all we perceive originates.
Writing my observations down like this helps me flesh out views that fall outside the mainstream paradigm. Sure, this feels a little unsettling at times. On balance though, seeing life from other angles is healthful, not heretical. I imagine most people would agree, at least until a particular view begins to threaten their own sacred cow. At that point, need, fear, and emotion (instinct) carries the day.