Recursive permutations

Private Sub Command1_Click()
Open "C:\windows\desktop\words.txt" For Output As #1
Recurse Text1.Text, ""   ' string so permutate is text1.text
Close #1
Shell "C:\windows\notepad.exe C:\windows\desktop\words.txt", vbNormalFocus
End Sub
Private Sub Recurse(ByVal Letters As String, ByVal Built As String)
Dim I As Integer
If Len(Letters) = 1 Then
Print #1, Built & Letters
Exit Sub
End If
For I = 1 To Len(Letters)
Recurse Mid(Letters, 1, I - 1) & Mid(Letters, I + 1), Built & Mid(Letters, I, 1)
Next I
End Sub