What is the order of basicity of amines?

My textbook claims that -



> 
> Greater is the stability of the substituted ammonium cation, stronger should be the corresponding amine as a base. Thus, the order of basicity of aliphatic amines should be: primary > secondary > tertiary.
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> 
> 


Now I have a problem with the first line.



> 
> Greater is the stability of the substituted ammonium cation, stronger should be the corresponding amine as a base.
> 
> 
> 


The substituted ammonium *cation* is a conjugate acid (because its lost a proton/$H^+$). So if the conj. acid is more stable then the corresponding amine should be more acidic and hence less basic. So is the textbook wrong or am I missing something here?


*Citation: Page 399, Chapter 13, NCERT Chemistry Part 2*




The sum of the $\mathrm{p}K\_\mathrm{b}$ value of a base and the $\mathrm{p}K\_\mathrm{a}$ value of its conjugate acid is a constant (at a constant temperature), and is equal to $\mathrm{p}K\_\mathrm{w}$ (which is $14$ at room temperature). The more stable the conjugate acid, the higher the $\mathrm{p}K\_\mathrm{a}$ of the conjugate acid $\implies$ lower $\mathrm{p}K\_\mathrm{b}$ of the amine $\implies$ more basic amine.


(For those who are reading this without reading the textbook, the quoted lines are part of an explanation of the order of basicity of amines; obviously the order of basicity of aliphatic amines does not follow the order primary > secondary > tertiary, as the quoted lines seem to imply out of context)


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