  We propose a parameterized proxy principle from which $\kappa$-Souslin trees
with various additional features can be constructed, regardless of the identity
of $\kappa$. We then introduce the microscopic approach, which is a simple
method for deriving trees from instances of the proxy principle. As a
demonstration, we give a construction of a coherent $\kappa$-Souslin tree that
applies also for $\kappa$ inaccessible.
  We then carry out a systematic study of the consistency of instances of the
proxy principle, distinguished by the vector of parameters serving as its
input. Among other things, it will be shown that all known $\diamondsuit$-based
constructions of $\kappa$-Souslin trees may be redirected through this new
proxy principle.
