  Slim semimodular lattices were introduced by G. Gr\"atzer and E. Knapp in
2007, and they have intensively been studied since then. It is often reasonable
to give these lattices by their $\mathcal C_1$-diagrams defined by the author
in 2017. We prove that if $x$ and $y$ are incomparable elements in such a
lattice $L$, then the interval $[x\wedge y, x]$ is a chain and this chain is of
a normal slope in every $\mathcal C_1$-diagram of $L$. Except possibly for $x$,
the elements of this chain are meet-reducible. If $A $ and $X$ are subsets of a
lattice $K$, then a sublattice $S$ of a lattice $L$ has the absorption property
$(K,A ,X)$ if for every embedding $g: K\to L$ such that $g(A)\subseteq S$, we
have that $g(X)\subseteq S$. If there is an idempotent endomorphism $f: L\to L$
such that $S=f(L)$, then the sublattice $S$ is a retract of $L$. Applying the
above-mentioned property of meets, we present two absorption properties that
the retracts of every slim semimodular lattice $L$ have.
