When you are in the world and the world seems real, and you feel like life is meaningless and empty, instead of seeking truly within you tend to seek without.
The ego has asserted that the absence of meaning is real, and that the truth is not already here. You fail to look within for it, believing it is not there now. So you start to look outside yourself for a substitute. Surely the meaning is out there and can be found, in the world?
This sets you on a path of seeking, at which the ego is chuckling because you're now falling for "seek and do not find", trying to find something out there which only exists within you.
The ego then reasons that it will keep the world real, but that somewhere within the world there is something worth finding. If you read the "laws of chaos", the ego's laws eventaully result in a desire to find something "special" within the external or in others - special love - which is substituting for the belief that you don't deserve or have real love already. It suggests you can really find it and that it will be your salvation.
Keeping the world means that any quest to find truth must find it within that context, so "the truth is out there". This immediately means that you will start to try to make some aspect of this world special and spiritual. Some aspects of it or some attitude about it will seem to be spiritual while others will seem to be unspiritual.
This is really the ego split mind which is perceiving some parts of what is as good and some as bad, trying to emphasize the good and reject the bad, which increases separation. The ego then begins to claim that the good stuff is "not the ego" and the bad stuff "is the ego". In the pretend name of getting rid of that which is unspiritual, it over-emphasizes that which it deems spiritual.
The good stuff is what your persona likes to keep, and the bad stuff is what you put into your "shadow" which is unconscious mostly. This results in you starting to try to change your persona, your conscious self, to "make it more spiritual".
So the ego has this entire path laid out for you, to "become more spiritual" by seeking externally and trying to find some alleged truth IN the world. This leads many people down a path which very much seems spiritual and positive and "better than the dark crap" but is actually an ILLUSION of spirituality.
While the ego is busy trying to make it seem like you're becoming more spiritual, you're actually moving away from your spiritual self (which is within, and was there all along), and is trying to get you to "find yourself" outside of yourself.
This leads to a variety of delusions such as that there is something sacred about the world, or the divine cosmos, or the universe is conscious and helping you, or that certain special objects or music or clothing or foods are all more spiritual.
It also leads the person's persona to become quite lost in the conceptual intellect, which is attempting to pretend to be spiritual way beyond what it is actually experiencing. It's attempt to reach out to lofty spiritual ideals is so far removed from "actual experience" that it can't help but go into the head and turn into a concept of the truth. It then believes it can find the truth by searching in the intellect or using the intellect to find it. This is a dead end.
It also causes the person or persona to become quite fake and filled with illusions of being spiritual. The trouble is, that the persona is a device for getting rid of anything about yourself that it deems not spiritual enough, and the only way to become really ultra spiritual is to get rid of as many bad parts as possible.
This turns into self sacrifice and a false idea of being selfless where you practically sell your soul in trying to be holier than thou. And in this you lose yourself, thinking that you're meant to serve and obey and do things you don't want to do. You'll take it very seriously and try to be as lofty and heightened in consciusness a possible, which usually translates to having a lot of thinking and conceptualizing. You then lose touch with reality, or at least, you lose touch with what you are really experiencing, and go into a fantasy land.
This fantasy land is the ego's idea of spirituality. It believes it can attain enlightenment and yet stay separate from God, becoming a God of its own making. This is a trap for every seeker. Everything spiritual-seeming, every illusion of spirituality, is offered up as a temptation or bribe to get you to actually abandon yourself and believe in the reality of an external truth even more. Believing in an external truth also means believing in an external God. Yet God is within you.
Sometimes that ego bubble bursts as the persona breaks down and the repressed rage of the shadow comes screaming into awareness to ask you to please acknowledge your real self and your actual experience, instead of your fictional life of ultra-specialness. This can be very unpleasant and come across as a form of insanity, but in a way it is a form of healing which is attempting to awaken you to the fact that your very own spiritualized persona is what has been destroying you all along, with its attempts to "perfect you" and transform you, instead of accepting you as you are.
These are difficult illusions to overcome, largely because the mind is unaware of what the persona is doing, and is unconscious of what it's shoving into the shadow. Many are led astray by this ego illusion of being spiritual. It is not really spiritual at all. There is no wholeness to it. There is a lack of authenticity to it. There is no real personality behind it.
Beware then, that as you attempt to become spiritual, the ego has an entire bucketload of tricks and temptations and traps and false masks for you to wear, to dress you up and make you look like you're being spiritual, even to yourself. And the only reason you fall for it is because you yourself believe that the truth is not in you. You agree with the ego that it is somewhere else and that you need to find it, which takes you on a long pointless journey to nowhere.
Once a seeker always a seeker, until you stop seeking and see the futility of it. What you are trying to find is yourself, and God, and truth and love. It's already in you. It's just covered up with illusions that make it seem like it is not there and cannot be there. But it is there. It was there all along. This is why the course asks us to remove the blocks to awareness of it, instead of seeking to find love somewhere else. We don't need a replacement for love, we just need to realize and accept where the love is.