穴 （  xue,  the second tone)  means 'cave‘ or ’hole‘ .  The top of 穴 looks like ‘roof' with the lower component  shapes as ’opening for entrance "..   

In Chinese 谷（gu, the third tone) looks like ‘valley’ which top looks like  the bird view of a mountain with deep opening  in it.   口(kou, the third tone) shapes as  the 'mouth'.  

Both 穴 and 谷 have a large space for you to hold something.  If you put 穴 and 谷 together，we get 容(rong,  the second tone) which basic meaning is ‘to hold or contain’ .   Passing through the gate 穴，you will see a great valley 谷.    What a wonderful landscape!

Of course，容 has multiple meanings:  volume, outlook，looking appearance，tolerance. ....