You could put the text into a text file and retrieve it as needed. But the users would have to keep the text file on their computer. Maybe a better option would be to declare your text as a constant in VBA then use it throughout as needed. Once the final doc is created, strip out the VBA code. Something like this perhaps:
Option Explicit
Public Const Text1 = "This is Text1"
Public Const Text2 = "This is Text2"
Public Const Text3 = "This is Text3"
Public Const Text4 = "This is Text4"
Sub Test()
Dim Choice As VbMsgBoxResult
Choice = InputBox("What Do You Want? (1-4)")
Select Case Choice
Case Is = 1
MsgBox Text1
Case Is = 2
MsgBox Text2
Case Is = 3
MsgBox Text3
Case Is = 4
MsgBox Text4
Case Else
MsgBox "Invalid selection, input a number from 1 to 4"
End Select
End Sub