You’re diving into copywriting to make money online, and that’s exciting.

You might already know copywriting is powerful, but what is it exactly?

I found a great definition in a training I read: “the use of words to persuade someone to take a specific action.” In simple terms, copywriting is about crafting messages (words, headlines, emails, ads, etc.) that resonate with people and move them to do something – like clicking a link, buying a product, or signing up for a call.

To really master copywriting, it helps to break it down into first principles – the fundamental truths behind the skill.

First principles are basic elements that can’t be broken down further.

Think of them like the building blocks of a house. If you understand these building blocks (first principles), you aren’t flying blind – you have true insight and control. In fact, the training emphasizes that understanding first principles is the key to success in copywriting (and in business generally).

So, what are these blocks for copywriting?

The piece I read breaks copywriting into three core elements: the Human we’re trying to reach, the Stimulus (our words or message), and the Action we want them to take.

In other words: Human + Stimulus → Action. (They even summarize it as Humans + Stimulus = Action.) When you deeply understand each element, copywriting becomes a lot more natural.


Let’s unpack them:

1. The Human (Audience) 👤:

Every bit of copywriting is aimed at people. People are made of mind and body, and the mind is key. To make someone act, you have to connect with their mind, because the mind drives the body to do things. This is why knowing psychology pays off. As an old advertising legend said, “the more psychology one knows, the better”.

The more you understand how people think and decide, the more effective your copy (stimulus) will be at creating action. For example, did you know that about 95% of our decisions happen subconsciously? Our brains form habits or “action-scripts” to save effort, so understanding those subconscious triggers can make your copy hit the mark. The better you know the inner workings of your reader’s mind, the easier it is to influence them.

Lock & Key (Heuristics):

A neat way to see this is the lock and key theory. Imagine the human mind as a lock and your copy as the key. To open the lock (get action), you need the right key shape.

Those shapes in the lock are called pins – in psychology, these are heuristics. Heuristics are mental shortcuts or cognitive biases our brains use to make decisions quickly. They’re like built-in rules of thumb.

Some copywriting tricks you’ve heard of actually work because they tap into these biases. For example, many people naturally want to stay consistent with their beliefs or seek confirmation of what they already think (that’s called confirmation bias).

A smart copywriter might use phrases like “It’s true…” or “They lied to you…” to play into that bias.

The training stresses: “Heuristics can be leveraged to cause humans to create the actions we want them to take.”. You don’t have to memorize dozens at once, but the more you learn about how people’s minds work (locks and their pins), the better you can craft your key (copy) to fit.

2. Stimuli (The Message):

In copywriting terms, a stimulus is anything you present to a person to trigger an action.

All copy — headlines, emails, button text, thumbnails, sales scripts, social posts — is really a form of stimulus.

Your job is to write effective stimuli: messages that actually cause the desired action.

That could mean writing an email subject line that makes someone open your email, a compelling headline that makes someone keep reading, or an ad that makes them click through.

Importantly, a stimulus isn’t just "good or bad" in isolation — it’s about how well it works with a specific audience.

A subject line that kills it with one group might flop with another. What we see is a spectrum of effectiveness, from 0% to 100%.

3. Latent Conditions:

This brings us to latent conditions. These are the hidden factors – what people in your niche already believe, feel, or are going through – that shape how they react to stimuli.

In short, an idea or headline might fail in one market and succeed wildly in another, depending on these conditions.

Think of latent conditions as the reader’s backdrop: their experiences, mood, desires, or pain points that day. For instance, many new copywriters share some common situations: maybe they’ve watched tons of free YouTube courses but never written much copy, or they know all the classic frameworks (AIDA, PAS, etc.) but freeze when facing a blank page.

Some feel decent about their copy but lack someone to give honest feedback, or struggle with imposter syndrome – one day believing they can succeed, another day doubting themselves.

They blame their niche for failures or dream of hitting $10k/month so everything will be great. These are all latent conditions (inner beliefs and feelings). By understanding these hidden factors, you can tailor your copy (stimulus) to meet them exactly where they are. In other words, the better you know your audience’s world (their lock’s pins), the better you can design the key.

For example, if you know a reader is skeptical about "get rich quick" promises, you wouldn’t start with hype – you might instead acknowledge their doubts and build trust. Understanding those doubts as latent conditions lets you choose words that resonate.

4. Action Chains:

Finally, let’s touch on micro and macro action chains.

In real life, persuading someone often happens step-by-step. You don’t just get a sale out of nowhere; you lead them through a series of small actions (micro actions) that add up to a big goal (macro action).

For instance, a cold outreach might go: a person opens your email, reads it, clicks a link, watches a short video, schedules a call, and then shows up to that call. Each step has its own piece of copy acting as a stimulus (an email subject line, the email body, a video thumbnail, a signup form, etc.).

If any one step fails (say, the subject line is boring and nobody opens the email), the whole chain can break. So we craft each message carefully, making sure every link in the chain smoothly leads to the next. When done right, this chain leads to the macro action you want – like booking a consultation or making a sale.

Putting it all together:

Copywriting is valuable because it’s at the heart of every business’s success. Every product or service needs persuasive words (stimuli) to reach people and cause action. By focusing on these first principles — knowing who you’re talking to (the Human), what you’re saying (Stimulus), and what you want them to do (Action) — you turn writing into a powerful tool. You’re not just guessing; you’re applying fundamental truths about people and how they decide.

Keep in mind: writing great copy also means testing and learning. No headline is perfect on the first try. The material reminds us to test, test, test, and refine based on what actually works. Over time, you’ll see patterns. Maybe certain words get more clicks, or certain topics really light up your audience. These are clues to the heuristics and latent conditions at play.

I know this sounds like a lot, but take it one step at a time. Start by remembering the definition: your words are a key to someone else’s lock. Learn a little psychology here and there (you can even find quick articles on common biases or human needs). Practice writing headlines and notice which ones you click on yourself. Write a short email and see if your friend would open it. As you do this, you’ll internalize these ideas naturally, almost without realizing it.

You’ve got this. These principles aren’t magic secrets — they’re simply honest ways of understanding people. The more you tune into how your readers think and feel, the easier it will be to write copy that feels right to them. And every time a piece of your copy works (someone clicks, signs up, or buys), you’ll feel that reward. Keep that excitement: with each small win, you’re that much closer to making a consistent income and helping people along the way.

Keep writing, keep testing, and remember: you have the keys now to many locks.

Cheers to your copywriting journey!

See you in the next principles!