Reliable Knowledge, and Yet More Filth

Question: I have a general Questionto ask regarding something I read many months ago in "The salvation of the soul".
a) I read that if a wet clean foot went into a najs dry shoe then as long no signs of najasat were seen on the foot, it can be regarded as clean. Is that right?
b) Likewise, if a wet clean body went onto a dry najs bed, then the body is to be considered clean as long as no signs of najasat were seen on it. Is that right?
c) Now, if a wet clean foot went into a wet najs shoe then the foot becomes najs regardless of whether the foot has any signs of najasat or not. Is that right?
d) Also, if a wet clean body goes onto a wet najs bed then the body becomes najs. Is that right?

My Questionis, if a wet clean body goes onto a dry bed, then eventually after a period of time, the bed will necessarily become wet, so if the body were to move a little then it would mean that a wet clean body is touching a wet najs bed, so it becomes najs regardless of there being any signs of najasat. Is this correct?

Walaikum assalam,
 
1. DO NOT READ The Salvation of the Soul, especially if you have waswasa. As Ustadha Umm Sahl, with her long years of study in Hanafi fiqh, notes, virtually every very page of the "translation" has mistakes in it, often very serious, sometimes completely changing the meaning. Knowledge is sacred, for it is ultimately from Allah, through His Noble Messenger (blessings and peace be upon him) as transmitted by his noble inheritors, the imams of our deen. As such, it is neither permitted nor valid to take this knowledge from other than reliable sources. A reliable source is either a person who reliably understands, or a text that discerning scholars consider to be reliable andthat one is able to understand. Answers to Questions and clarifications should be sought from a reliable person, rather than mere "personal investigation," unless one has the skill and means to make such investigation reliably. This is understood from Allah Most High's command to, "Ask the people of remembrance (ahl al-dhikr) if you do not know."
 
Sayyidna Ali (may Allah ennoble his countenance) said, "This matter is your deen, so be careful whom you take your deen from." Had he lived to see the advent of the printed press, he would have added, "where."
 
The answer to (a) to (d) is that they are right.
 
(a) to (c) are explained by the fact that the clean surface is certainly tahir. By merely touching the najas surface, we have reason to think that the najasa (filth) may have transferred. This is not sufficient to lift the initial certainty because, "Certainty is not lifted by doubt but, rather, only by another certainty." Doubt here refers to anything less than certainty, including our reasoned suppositions.
 
Scholars tell us that issues of tahara are based on acting upon the outward signs, not on our reasoning. Excessive reasoning about issues of tahara/najasa is the door to the pits of waswasa.
 
As for your final Question, it is excessive reasoning. Why would you go into a wet bed, with wet najasa on your body?
 
And Allah knows best.
 
Wassalam,
Faraz.